Metal: use atomic for buffer tracking

2025-09-19 13:41:37 -07:00
159 changed files with 1490 additions and 5830 deletions
@@ -12,7 +12,7 @@ jobs:
    name: build-android
    # We intentially use a larger runner here to enable larger disk space
    # (standard linux runner will fail on disk space and faster build time).
-    runs-on: 'ubuntu-24.04-16core'
+    runs-on: 'ubuntu-24.04-32core'

    steps:
      - uses: actions/checkout@v4.1.6
@@ -26,7 +26,7 @@ jobs:

  build-desktop-linux:
    name: build-linux
-    runs-on: 'ubuntu-24.04-16core'
+    runs-on: ubuntu-22.04-16core
    steps:
      - uses: actions/checkout@v4.1.6
        with:
@@ -171,7 +171,7 @@ jobs:

  validate-wgsl-webgpu:
    name: validate-wgsl-webgpu
-    runs-on: 'ubuntu-24.04-16core'
+    runs-on: 'ubuntu-24.04-8core'
    steps:
      - uses: actions/checkout@v4.1.6
        with:
@@ -31,7 +31,7 @@ on:
 jobs:
  build-linux:
    name: build-linux
-    runs-on: 'ubuntu-24.04-16core'
+    runs-on: ubuntu-22.04-32core
    if: github.event_name == 'release' || github.event.inputs.platform == 'desktop'

    steps:
@@ -18,9 +18,3 @@ test*.json
 results
 /compile_commands.json
 /.cache
-
-# For /test/renderdiff dependencies
-/mesa
-/gltf
-/filament-assets
-/venv
@@ -31,7 +31,7 @@ repositories {
 }

 dependencies {
-    implementation 'com.google.android.filament:filament-android:1.65.4'
+    implementation 'com.google.android.filament:filament-android:1.65.0'
 }
 ```

@@ -51,7 +51,7 @@ Here are all the libraries available in the group `com.google.android.filament`:
 iOS projects can use CocoaPods to install the latest release:

 ```shell
-pod 'Filament', '~> 1.65.4'
+pod 'Filament', '~> 1.65.0'
 ```

 ## Documentation
@@ -7,15 +7,6 @@ A new header is inserted each time a *tag* is created.
 Instead, if you are authoring a PR for the main branch, add your release note to
 [NEW_RELEASE_NOTES.md](./NEW_RELEASE_NOTES.md).

-## v1.65.4
-
-
-## v1.65.3
-
-
-## v1.65.2
-
-
 ## v1.65.1

 - `setFrameScheduledCallback` now works on all backends (frame presentation scheduling is still only
@@ -28,8 +28,9 @@ Java_com_google_android_filament_SwapChain_nSetFrameCompletedCallback(JNIEnv* en
        jlong nativeSwapChain, jobject handler, jobject runnable) {
    SwapChain* swapChain = (SwapChain*) nativeSwapChain;
    auto* callback = JniCallback::make(env, handler, runnable);
-    swapChain->setFrameCompletedCallback(callback->getHandler(),
-            [callback](SwapChain* swapChain) { JniCallback::postToJavaAndDestroy(callback); });
+    swapChain->setFrameCompletedCallback(nullptr, [callback](SwapChain* swapChain) {
+        JniCallback::postToJavaAndDestroy(callback);
+    });
 }

 extern "C" JNIEXPORT jboolean JNICALL
@@ -52,22 +53,3 @@ Java_com_google_android_filament_SwapChain_nIsProtectedContentSupported(
    Engine* engine = (Engine*) nativeEngine;
    return (jboolean)SwapChain::isProtectedContentSupported(*engine);
 }
-
-extern "C" JNIEXPORT void JNICALL
-Java_com_google_android_filament_SwapChain_nSetFrameScheduledCallback(JNIEnv* env, jclass,
-        jlong nativeSwapChain, jobject handler, jobject runnable) {
-    SwapChain* swapChain = (SwapChain*) nativeSwapChain;
-    auto* callback = JniCallback::make(env, handler, runnable);
-    swapChain->setFrameScheduledCallback(callback->getHandler(),
-            [callback](backend::PresentCallable) {
-                // Ignore PresentCallable, which is only meaningful with the Metal backend.
-                JniCallback::postToJavaAndDestroy(callback);
-            });
-}
-
-extern "C" JNIEXPORT jboolean JNICALL
-Java_com_google_android_filament_SwapChain_nIsFrameScheduledCallbackSet(
-        JNIEnv *, jclass, jlong nativeSwapChain) {
-    SwapChain* swapChain = (SwapChain*) nativeSwapChain;
-    return (jboolean)swapChain->isFrameScheduledCallbackSet();
-}
@@ -139,78 +139,6 @@ public class SwapChain {
        nSetFrameCompletedCallback(getNativeObject(), handler, callback);
    }

-    /**
-     * FrameScheduledCallback is a callback function that notifies an application about the status
-     * of a frame after Filament has finished its processing.
-     *
-     * <p>
-     * The exact timing and semantics of this callback differ depending on the graphics backend in
-     * use.
-     * </p>
-     *
-     * <h3>Metal Backend</h3>
-     * <p>
-     * With the Metal backend, this callback signifies that Filament has completed all CPU-side
-     * processing for a frame and the frame is ready to be scheduled for presentation.
-     * </p>
-     *
-     * <p>
-     * Typically, Filament is responsible for scheduling the frame's presentation to the SwapChain.
-     * If a FrameScheduledCallback is set, however, the application bears the responsibility of
-     * scheduling the frame for presentation by calling the PresentCallable passed to the callback
-     * function. In this mode, Filament will not automatically schedule the frame for presentation.
-     * </p>
-     *
-     * <p>
-     * When using the Metal backend, if your application delays the call to the PresentCallable
-     * (e.g., by invoking it on a separate thread), you must ensure all PresentCallables have been
-     * called before shutting down the Filament Engine. You can guarantee this by calling
-     * Engine.flushAndWait() before Engine.shutdown(). This is necessary to ensure the Engine has
-     * a chance to clean up all memory related to frame presentation.
-     * </p>
-     *
-     * <h3>Other Backends (OpenGL, Vulkan, WebGPU)</h3>
-     * <p>
-     * On other backends, this callback serves as a notification that Filament has completed all
-     * CPU-side processing for a frame. Filament proceeds with its normal presentation logic
-     * automatically, and the PresentCallable passed to the callback is a no-op that can be safely
-     * ignored.
-     * </p>
-     *
-     * <h3>General Behavior</h3>
-     * <p>
-     * A FrameScheduledCallback can be set on an individual SwapChain through
-     * setFrameScheduledCallback. Each SwapChain can have only one callback set per frame. If
-     * setFrameScheduledCallback is called multiple times on the same SwapChain before
-     * Renderer.endFrame(), the most recent call effectively overwrites any previously set callback.
-     * </p>
-     *
-     * <p>
-     * The callback set by setFrameScheduledCallback is "latched" when Renderer.endFrame() is
-     * executed. At this point, the callback is fixed for the frame that was just encoded.
-     * Subsequent calls to setFrameScheduledCallback after endFrame() will apply to the next frame.
-     * </p>
-     *
-     * <p>
-     * Use setFrameScheduledCallback() (with default arguments) to unset the callback.
-     * </p>
-     *
-     * @param handler     A {@link java.util.concurrent.Executor Executor}.
-     * @param callback    The Runnable callback to invoke when frame processing is complete.
-     */
-    public void setFrameScheduledCallback(@NonNull Object handler, @NonNull Runnable callback) {
-        nSetFrameScheduledCallback(getNativeObject(), handler, callback);
-    }
-
-    /**
-     * Returns whether this SwapChain currently has a FrameScheduledCallback set.
-     *
-     * @return true, if the last call to setFrameScheduledCallback set a callback
-     */
-    public boolean isFrameScheduledCallbackSet() {
-        return nIsFrameScheduledCallbackSet(getNativeObject());
-    }
-
    public long getNativeObject() {
        if (mNativeObject == 0) {
            throw new IllegalStateException("Calling method on destroyed SwapChain");
@@ -223,8 +151,6 @@ public class SwapChain {
    }

    private static native void nSetFrameCompletedCallback(long nativeSwapChain, Object handler, Runnable callback);
-    private static native void nSetFrameScheduledCallback(long nativeSwapChain, Object handler, Runnable callback);
-    private static native boolean nIsFrameScheduledCallbackSet(long nativeSwapChain);
    private static native boolean nIsSRGBSwapChainSupported(long nativeEngine);
    private static native boolean nIsMSAASwapChainSupported(long nativeEngine, int samples);
    private static native boolean nIsProtectedContentSupported(long nativeEngine);
@@ -1,5 +1,5 @@
 GROUP=com.google.android.filament
-VERSION_NAME=1.65.4
+VERSION_NAME=1.65.0

 POM_DESCRIPTION=Real-time physically based rendering engine for Android.

@@ -24,7 +24,7 @@ android {

    compileSdkVersion versions.compileSdk
    defaultConfig {
-        applicationId "com.google.android.filament.hellocam"
+        applicationId "com.google.android.filament.hellocamera"
        minSdkVersion 23
        targetSdkVersion versions.targetSdk
    }
@@ -181,7 +181,7 @@ important for <code>matc</code> (material compiler).</p>
 }

 dependencies {
-    implementation 'com.google.android.filament:filament-android:1.65.2'
+    implementation 'com.google.android.filament:filament-android:1.65.0'
 }
 </code></pre>
 <p>Here are all the libraries available in the group <code>com.google.android.filament</code>:</p>
@@ -196,7 +196,7 @@ dependencies {
 </div>
 <h3 id="ios"><a class="header" href="#ios">iOS</a></h3>
 <p>iOS projects can use CocoaPods to install the latest release:</p>
-<pre><code class="language-shell">pod 'Filament', '~&gt; 1.65.2'
+<pre><code class="language-shell">pod 'Filament', '~&gt; 1.65.0'
 </code></pre>
 <h2 id="documentation"><a class="header" href="#documentation">Documentation</a></h2>
 <ul>
@@ -1,330 +0,0 @@
-<!DOCTYPE HTML>
-<html lang="en" class="light sidebar-visible" dir="ltr">
-    <head>
-        <!-- Book generated using mdBook -->
-        <meta charset="UTF-8">
-        <title>renderdiff - Filament</title>
-
-
-        <!-- Custom HTML head -->
-
-        <meta name="description" content="">
-        <meta name="viewport" content="width=device-width, initial-scale=1">
-        <meta name="theme-color" content="#ffffff">
-
-        <link rel="shortcut icon" href="../favicon.png">
-        <link rel="stylesheet" href="../css/variables.css">
-        <link rel="stylesheet" href="../css/general.css">
-        <link rel="stylesheet" href="../css/chrome.css">
-
-        <!-- Fonts -->
-        <link rel="stylesheet" href="../FontAwesome/css/font-awesome.css">
-        <link rel="stylesheet" href="../fonts/fonts.css">
-
-        <!-- Highlight.js Stylesheets -->
-        <link rel="stylesheet" href="../highlight.css">
-        <link rel="stylesheet" href="../tomorrow-night.css">
-        <link rel="stylesheet" href="../ayu-highlight.css">
-
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-        <script async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
-
-        <!-- Provide site root to javascript -->
-        <script>
-            var path_to_root = "../";
-            var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "light" : "light";
-        </script>
-        <!-- Start loading toc.js asap -->
-        <script src="../toc.js"></script>
-    </head>
-    <body>
-    <div id="body-container">
-        <!-- Work around some values being stored in localStorage wrapped in quotes -->
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-            try {
-                var theme = localStorage.getItem('mdbook-theme');
-                var sidebar = localStorage.getItem('mdbook-sidebar');
-
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-            var theme;
-            try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
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-            const html = document.documentElement;
-            html.classList.remove('light')
-            html.classList.add(theme);
-            html.classList.add("js");
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-                try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
-                sidebar = sidebar || 'visible';
-            } else {
-                sidebar = 'hidden';
-            }
-            sidebar_toggle.checked = sidebar === 'visible';
-            html.classList.remove('sidebar-visible');
-            html.classList.add("sidebar-" + sidebar);
-        </script>
-
-        <nav id="sidebar" class="sidebar" aria-label="Table of contents">
-            <div style="display:flex;align-items:center;justify-content:center">
-                <img class="flogo" src="../images/filament_logo_small.png"></img>
-            </div>
-            <!-- populated by js -->
-            <mdbook-sidebar-scrollbox class="sidebar-scrollbox"></mdbook-sidebar-scrollbox>
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-                        <!-- Filament: disable themes because the markdeep part does not look good for dark themes -->
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-                    </div>
-
-                    <h1 class="menu-title">Filament</h1>
-
-                    <div class="right-buttons">
-                        <a href="https://github.com/google/filament" title="Git repository" aria-label="Git repository">
-                            <i id="git-repository-button" class="fa fa-github"></i>
-                        </a>
-
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-                        <input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
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-                    Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
-                        link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
-                    });
-                </script>
-
-                <div id="content" class="content">
-                    <main>
-                        <h1 id="rendering-difference-test"><a class="header" href="#rendering-difference-test">Rendering Difference Test</a></h1>
-<p>We created a few scripts to run <code>gltf_viewer</code> and produce headless renderings.</p>
-<p>This is mainly useful for continuous integration where GPUs are generally not available on cloud
-machines. To perform software rasterization, these scripts are centered around <a href="https://docs.mesa3d.org">Mesa</a>'s
-software rasterizers, but nothing bars us from using another rasterizer like <a href="https://github.com/google/swiftshader">SwiftShader</a>.
-Additionally, we should be able to use GPUs where available (though this is more of a future
-work).</p>
-<p>The script <code>render.py</code> contains the core logic for taking input parameters (such as the test
-description file) and then running gltf_viewer to produce the renderings.</p>
-<p>In the <code>test</code> directory is a list of test descriptions that are specified in json. Please see
-<code>sample.json</code> to parse the structure.</p>
-<h2 id="setting-up-python"><a class="header" href="#setting-up-python">Setting up python</a></h2>
-<p>The <code>renderdiff</code> project uses <code>python</code> extensively. To install the dependencies for producing
-renderings, do the following step</p>
-<ul>
-<li>Set up a virtual environment (from the root directory)
-<pre><code>python3 -m venv venv
-. ./venv/bin/activate
-</code></pre>
-</li>
-<li>Install the rendering dependencies
-<pre><code>pip install -r test/renderdiff/src/rendering_requirements.txt
-</code></pre>
-</li>
-<li>Install the viewer depdencies
-<pre><code>pip install -r test/renderdiff/src/viewer_requirements.txt
-</code></pre>
-</li>
-<li>For the commands in the following section, do not exit the virtual environment. Once you've
-completed all your work, you can exit with
-<pre><code>deactivate
-</code></pre>
-</li>
-</ul>
-<h2 id="running-the-test-locally"><a class="header" href="#running-the-test-locally">Running the test locally</a></h2>
-<ul>
-<li>To run the same presbumit as <a href="presubmit-renderdiff"><code>test-renderdiff</code></a>, you can do
-<pre><code>bash test/renderdiff/local_test.sh
-</code></pre>
-</li>
-<li>This script will generate the renderings based on the current state of your repo.
-Additionally, it will also compare the generated images with corresponding images in the
-golden repo.</li>
-<li>To just render without running the test, you could use the following script
-<pre><code>bash test/renderdiff/generate.sh
-</code></pre>
-</li>
-</ul>
-<h2 id="filtering-tests"><a class="header" href="#filtering-tests">Filtering Tests</a></h2>
-<p>You can run a subset of the tests by passing the <code>--test_filter</code> flag to <code>local_test.sh</code>. The
-filter supports wildcards (<code>*</code>) to match test names. For example, to run all tests in the
-<code>ClearCoat</code> suite, you can use the following command:</p>
-<pre><code>bash test/renderdiff/local_test.sh --test_filter='ClearCoat.*.*'
-</code></pre>
-<h2 id="update-the-golden-images"><a class="header" href="#update-the-golden-images">Update the golden images</a></h2>
-<p>The golden images are stored in a github repository:
-https://github.com/google/filament-assets. Filament team members should have access to write
-to the repository. A typical flow for updating the goldens is to upload your changed images
-into <strong>branch</strong> of <code>filament-assets</code>. This branch is paired with a PR or commit on the
-<code>filament</code> repo.</p>
-<p>As an example, imagine I am working on a PR, and I've uploaded my change, which is in a
-branch called <code>my-pr-branch</code>, to <code>filament</code>. This PR requires updating the golden. We would do
-it in the following fashion</p>
-<h3 id="using-a-script-to-update-the-golden-repo"><a class="header" href="#using-a-script-to-update-the-golden-repo">Using a script to update the golden repo</a></h3>
-<ul>
-<li>Run interactive mode in the <code>update_golden.py</code> script.
-<pre><code>python3 test/renderdiff/src/update_golden.py
-</code></pre>
-</li>
-<li>This will guide you through a series of steps to push the changes to a remote branch on
-<code>filament-assets</code>.</li>
-</ul>
-<h3 id="manually-updating-the-golden-repo"><a class="header" href="#manually-updating-the-golden-repo">Manually updating the golden repo</a></h3>
-<ul>
-<li>Check out the golden repo
-<pre><code>git clone git@github.com:google/filament-assets.git
-</code></pre>
-</li>
-<li>Create a branch on the golden repo
-<pre><code>cd filament-assets
-git switch -c my-pr-branch-golden
-</code></pre>
-</li>
-<li>Copy the new images to their appropriate place in <code>filament-assets</code></li>
-<li>Push the <code>filament-assets</code> working branch to remote
-<pre><code>git push origin my-pr-branch-golden
-</code></pre>
-</li>
-<li>In the commit message of your working branch on <code>filament</code>, add the following line
-<pre><code>RDIFF_BBRANCH=my-pr-branch-golden
-</code></pre>
-</li>
-</ul>
-<p>Doing the above has multiple effects:</p>
-<ul>
-<li>The presubmit test <a href="https://github.com/google/filament/blob/e85dfe75c86106a05019e13ccdbef67e030af675/.github/workflows/presubmit.yml#L118"><code>test-renderdiff</code></a> will test against the provided
-branch of the golden repo (i.e. <code>my-pr-branch-golden</code>).</li>
-<li>If the PR is merged, then there is another workflow that will merge <code>my-pr-branch-golden</code>
-to the <code>main</code> branch of the golden repo.</li>
-</ul>
-<h2 id="viewing-test-results"><a class="header" href="#viewing-test-results">Viewing test results</a></h2>
-<p>We provide a viewer for looking at the result of a test run. The viewer is a webapp that can
-be used by pointing your browser to a localhost port. If you input the viewer with a PR or a
-directory, it will parse the test result and show the results and the rendered and/or golden
-images.</p>
-<p><img src="../images/renderdiff_example.png" alt="Viewer" /></p>
-<p>To run the viewer of a test output directory that has been generated locally, you would run
-the following</p>
-<pre><code>python3 test/renderdiff/src/viewer.py --diff=[test output]
-</code></pre>
-<p>where <code>[test output]</code> is a directory containing the <code>compare_results.json</code> of the test run.
-For example, it could be <code>out/renderdiff/diffs/presubmit</code> for the standard path to the
-<code>presubmit</code> test output.</p>
-<p>To see the results of a Pull Request initiated test run, you would do the following</p>
-<pre><code>python3 test/renderdiff/src/viewer.py --pr_number=[PR #] --github_token=[github token]
-</code></pre>
-<p>where <code>[PR #]</code> is the numeric ID of your pull request, and the <code>[github token]</code> is an acess
-token that you (as a github user) needs to generate (<a href="https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/managing-your-personal-access-tokens">reference</a>).</p>
-
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-                    <a rel="next prefetch" href="../notes/libs.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
-                        <i class="fa fa-angle-right"></i>
-                    </a>
-            </nav>
-
-        </div>
-
-
-
-
-        <script>
-            window.playground_copyable = true;
-        </script>
-
-
-        <script src="../elasticlunr.min.js"></script>
-        <script src="../mark.min.js"></script>
-        <script src="../searcher.js"></script>
-
-        <script src="../clipboard.min.js"></script>
-        <script src="../highlight.js"></script>
-        <script src="../book.js"></script>
-
-        <!-- Custom JS scripts -->
-
-
-    </div>
-    </body>
-</html>
@@ -335,7 +335,7 @@ nodes</li>
                                <i class="fa fa-angle-left"></i>
                            </a>

-                            <a rel="next prefetch" href="../notes/tests.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
+                            <a rel="next prefetch" href="../notes/libs.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
                                <i class="fa fa-angle-right"></i>
                            </a>

@@ -349,7 +349,7 @@ nodes</li>
                        <i class="fa fa-angle-left"></i>
                    </a>

-                    <a rel="next prefetch" href="../notes/tests.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
+                    <a rel="next prefetch" href="../notes/libs.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
                        <i class="fa fa-angle-right"></i>
                    </a>
            </nav>
@@ -165,7 +165,7 @@

                    <nav class="nav-wrapper" aria-label="Page navigation">
                        <!-- Mobile navigation buttons -->
-                            <a rel="prev" href="../dup/renderdiff.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
+                            <a rel="prev" href="../notes/framegraph.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
                                <i class="fa fa-angle-left"></i>
                            </a>

@@ -179,7 +179,7 @@
            </div>

            <nav class="nav-wide-wrapper" aria-label="Page navigation">
-                    <a rel="prev" href="../dup/renderdiff.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
+                    <a rel="prev" href="../notes/framegraph.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
                        <i class="fa fa-angle-left"></i>
                    </a>

@@ -1,215 +0,0 @@
-<!DOCTYPE HTML>
-<html lang="en" class="light sidebar-visible" dir="ltr">
-    <head>
-        <!-- Book generated using mdBook -->
-        <meta charset="UTF-8">
-        <title>Tests - Filament</title>
-
-
-        <!-- Custom HTML head -->
-
-        <meta name="description" content="">
-        <meta name="viewport" content="width=device-width, initial-scale=1">
-        <meta name="theme-color" content="#ffffff">
-
-        <link rel="shortcut icon" href="../favicon.png">
-        <link rel="stylesheet" href="../css/variables.css">
-        <link rel="stylesheet" href="../css/general.css">
-        <link rel="stylesheet" href="../css/chrome.css">
-
-        <!-- Fonts -->
-        <link rel="stylesheet" href="../FontAwesome/css/font-awesome.css">
-        <link rel="stylesheet" href="../fonts/fonts.css">
-
-        <!-- Highlight.js Stylesheets -->
-        <link rel="stylesheet" href="../highlight.css">
-        <link rel="stylesheet" href="../tomorrow-night.css">
-        <link rel="stylesheet" href="../ayu-highlight.css">
-
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-        <script async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
-
-        <!-- Provide site root to javascript -->
-        <script>
-            var path_to_root = "../";
-            var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "light" : "light";
-        </script>
-        <!-- Start loading toc.js asap -->
-        <script src="../toc.js"></script>
-    </head>
-    <body>
-    <div id="body-container">
-        <!-- Work around some values being stored in localStorage wrapped in quotes -->
-        <script>
-            try {
-                var theme = localStorage.getItem('mdbook-theme');
-                var sidebar = localStorage.getItem('mdbook-sidebar');
-
-                if (theme.startsWith('"') && theme.endsWith('"')) {
-                    localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
-                }
-
-                if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
-                    localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
-                }
-            } catch (e) { }
-        </script>
-
-        <!-- Set the theme before any content is loaded, prevents flash -->
-        <script>
-            var theme;
-            try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
-            if (theme === null || theme === undefined) { theme = default_theme; }
-            const html = document.documentElement;
-            html.classList.remove('light')
-            html.classList.add(theme);
-            html.classList.add("js");
-        </script>
-
-        <input type="checkbox" id="sidebar-toggle-anchor" class="hidden">
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-            var sidebar = null;
-            var sidebar_toggle = document.getElementById("sidebar-toggle-anchor");
-            if (document.body.clientWidth >= 1080) {
-                try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
-                sidebar = sidebar || 'visible';
-            } else {
-                sidebar = 'hidden';
-            }
-            sidebar_toggle.checked = sidebar === 'visible';
-            html.classList.remove('sidebar-visible');
-            html.classList.add("sidebar-" + sidebar);
-        </script>
-
-        <nav id="sidebar" class="sidebar" aria-label="Table of contents">
-            <div style="display:flex;align-items:center;justify-content:center">
-                <img class="flogo" src="../images/filament_logo_small.png"></img>
-            </div>
-            <!-- populated by js -->
-            <mdbook-sidebar-scrollbox class="sidebar-scrollbox"></mdbook-sidebar-scrollbox>
-            <noscript>
-                <iframe class="sidebar-iframe-outer" src="../toc.html"></iframe>
-            </noscript>
-            <div id="sidebar-resize-handle" class="sidebar-resize-handle">
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-            </div>
-        </nav>
-
-        <div id="page-wrapper" class="page-wrapper">
-
-            <div class="page">
-                <div id="menu-bar-hover-placeholder"></div>
-                <div id="menu-bar" class="menu-bar sticky">
-                    <div class="left-buttons">
-                        <label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
-                            <i class="fa fa-bars"></i>
-                        </label>
-                        <!-- Filament: disable themes because the markdeep part does not look good for dark themes -->
-                        <!--
-                        <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
-                            <i class="fa fa-paint-brush"></i>
-                        </button>
-                        <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
-                            <li role="none"><button role="menuitem" class="theme" id="light">Light</button></li>
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-                        </ul>
-                        -->
-                        <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
-                            <i class="fa fa-search"></i>
-                        </button>
-                    </div>
-
-                    <h1 class="menu-title">Filament</h1>
-
-                    <div class="right-buttons">
-                        <a href="https://github.com/google/filament" title="Git repository" aria-label="Git repository">
-                            <i id="git-repository-button" class="fa fa-github"></i>
-                        </a>
-
-                    </div>
-                </div>
-
-                <div id="search-wrapper" class="hidden">
-                    <form id="searchbar-outer" class="searchbar-outer">
-                        <input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
-                    </form>
-                    <div id="searchresults-outer" class="searchresults-outer hidden">
-                        <div id="searchresults-header" class="searchresults-header"></div>
-                        <ul id="searchresults">
-                        </ul>
-                    </div>
-                </div>
-
-                <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
-                <script>
-                    document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
-                    document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
-                    Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
-                        link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
-                    });
-                </script>
-
-                <div id="content" class="content">
-                    <main>
-                        <h1 id="tests"><a class="header" href="#tests">Tests</a></h1>
-<p>Filament has a collection of tests that can be run locally. Many of them are used
-for in our Continuation Integration flow <a href="https://https://github.com/google/filament/tree/main/.github/workflows">on github</a>.</p>
-
-                    </main>
-
-                    <nav class="nav-wrapper" aria-label="Page navigation">
-                        <!-- Mobile navigation buttons -->
-                            <a rel="prev" href="../notes/framegraph.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
-                                <i class="fa fa-angle-left"></i>
-                            </a>
-
-                            <a rel="next prefetch" href="../dup/renderdiff.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
-                                <i class="fa fa-angle-right"></i>
-                            </a>
-
-                        <div style="clear: both"></div>
-                    </nav>
-                </div>
-            </div>
-
-            <nav class="nav-wide-wrapper" aria-label="Page navigation">
-                    <a rel="prev" href="../notes/framegraph.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
-                        <i class="fa fa-angle-left"></i>
-                    </a>
-
-                    <a rel="next prefetch" href="../dup/renderdiff.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
-                        <i class="fa fa-angle-right"></i>
-                    </a>
-            </nav>
-
-        </div>
-
-
-
-
-        <script>
-            window.playground_copyable = true;
-        </script>
-
-
-        <script src="../elasticlunr.min.js"></script>
-        <script src="../mark.min.js"></script>
-        <script src="../searcher.js"></script>
-
-        <script src="../clipboard.min.js"></script>
-        <script src="../highlight.js"></script>
-        <script src="../book.js"></script>
-
-        <!-- Custom JS scripts -->
-
-
-    </div>
-    </body>
-</html>
@@ -78,11 +78,5 @@
    },
    "docs_src/README.md": {
        "dest": "dup/docs.md"
-    },
-    "test/renderdiff/README.md": {
-        "dest": "dup/renderdiff.md",
-        "link_transforms": {
-            "docs/images/": "../images/"
-        }
    }
 }
@@ -27,8 +27,6 @@
    - [Code coverage analysis](./notes/coverage.md)
    - [Performance analysis](./notes/performance_analysis.md)
  - [Framegraph](./notes/framegraph.md)
-  - [Tests](./notes/tests.md)
-    - [renderdiff](./dup/renderdiff.md)
  - [Libraries](./notes/libs.md)
    - [bluegl](./dup/bluegl.md)
    - [bluevk](./dup/bluevk.md)
@@ -1,4 +0,0 @@
-# Tests
-
-Filament has a collection of tests that can be run locally. Many of them are used
-for in our Continuation Integration flow [on github](https://https://github.com/google/filament/tree/main/.github/workflows).
@@ -84,8 +84,6 @@ set(SRCS
        src/InstanceBuffer.cpp
        src/LightManager.cpp
        src/Material.cpp
-        src/MaterialCache.cpp
-        src/MaterialDefinition.cpp
        src/MaterialInstance.cpp
        src/MaterialInstanceManager.cpp
        src/MaterialParser.cpp
@@ -177,8 +175,6 @@ set(PRIVATE_HDRS
        src/HwRenderPrimitiveFactory.h
        src/HwVertexBufferInfoFactory.h
        src/Intersections.h
-        src/MaterialCache.h
-        src/MaterialDefinition.h
        src/MaterialParser.h
        src/MaterialInstanceManager.h
        src/PIDController.h
@@ -78,8 +78,6 @@ if (FILAMENT_SUPPORTS_OPENGL AND NOT FILAMENT_USE_EXTERNAL_GLES3)
            src/opengl/GLTexture.h
            src/opengl/GLUtils.cpp
            src/opengl/GLUtils.h
-            src/opengl/GLMemoryMappedBuffer.cpp
-            src/opengl/GLMemoryMappedBuffer.h
            src/opengl/OpenGLBlobCache.cpp
            src/opengl/OpenGLBlobCache.h
            src/opengl/OpenGLContext.cpp
@@ -179,7 +177,6 @@ endif()
 if (FILAMENT_SUPPORTS_VULKAN)
    list(APPEND SRCS
            include/backend/platforms/VulkanPlatform.h
-            src/vulkan/VulkanAsyncHandles.cpp
            src/vulkan/VulkanAsyncHandles.h
            src/vulkan/VulkanBlitter.cpp
            src/vulkan/VulkanBlitter.h
@@ -218,10 +215,6 @@ if (FILAMENT_SUPPORTS_VULKAN)
            src/vulkan/VulkanReadPixels.h
            src/vulkan/VulkanSamplerCache.cpp
            src/vulkan/VulkanSamplerCache.h
-            src/vulkan/VulkanSemaphore.cpp
-            src/vulkan/VulkanSemaphore.h
-            src/vulkan/VulkanSemaphoreManager.cpp
-            src/vulkan/VulkanSemaphoreManager.h
            src/vulkan/VulkanStagePool.cpp
            src/vulkan/VulkanStagePool.h
            src/vulkan/VulkanSwapChain.cpp
@@ -573,7 +566,6 @@ if (APPLE OR LINUX)
        test/test_ReadPixels.cpp
        test/test_BufferUpdates.cpp
        test/test_Callbacks.cpp
-        test/test_MemoryMappedBuffer.cpp
        test/test_MRT.cpp
        test/test_PushConstants.cpp
        test/test_LoadImage.cpp
@@ -197,7 +197,6 @@ constexpr std::string_view to_string(Backend const backend) noexcept {
 * - The Metal backend can prefer precompiled Metal libraries, while falling back to MSL.
 */
 enum class ShaderLanguage {
-    UNSPECIFIED = -1,
    ESSL1 = 0,
    ESSL3 = 1,
    SPIRV = 2,
@@ -220,8 +219,6 @@ constexpr const char* shaderLanguageToString(ShaderLanguage shaderLanguage) noex
            return "Metal precompiled library";
        case ShaderLanguage::WGSL:
            return "WGSL";
-        case ShaderLanguage::UNSPECIFIED:
-            return "Unspecified";
    }
    return "UNKNOWN";
 }
@@ -559,21 +556,12 @@ constexpr TargetBufferFlags getTargetBufferFlagsAt(size_t index) noexcept {
 }

 /**
- * How the buffer will be used.
+ * Frequency at which a buffer is expected to be modified and used. This is used as an hint
+ * for the driver to make better decisions about managing memory internally.
 */
 enum class BufferUsage : uint8_t {
-    STATIC              = 0,    //!< (legacy) content modified once, used many times
-    DYNAMIC             = 1,    //!< (legacy) content modified frequently, used many times
-    DYNAMIC_BIT         = 0x1,  //!< buffer can be modified frequently, used many times
-    SHARED_WRITE_BIT    = 0x04, //!< buffer can be memory mapped for write operations
-};
-
-/**
- * How the buffer will be mapped.
- */
-enum class MapBufferAccessFlags : uint8_t {
-    WRITE_BIT               = 0x2,  //!< buffer is mapped from writing
-    INVALIDATE_RANGE_BIT    = 0x4,  //!< the mapped range content is lost
+    STATIC,      //!< content modified once, used many times
+    DYNAMIC,     //!< content modified frequently, used many times
 };

 /**
@@ -639,15 +627,6 @@ enum class ShaderModel : uint8_t {
 };
 static constexpr size_t SHADER_MODEL_COUNT = 2;

-constexpr std::string_view to_string(ShaderModel model) noexcept {
-    switch (model) {
-        case ShaderModel::MOBILE:
-            return "mobile";
-        case ShaderModel::DESKTOP:
-            return "desktop";
-    }
-}
-
 /**
 * Primitive types
 */
@@ -1713,11 +1692,6 @@ template<> struct utils::EnableBitMaskOperators<filament::backend::TextureUsage>
        : public std::true_type {};
 template<> struct utils::EnableBitMaskOperators<filament::backend::StencilFace>
        : public std::true_type {};
-template<> struct utils::EnableBitMaskOperators<filament::backend::BufferUsage>
-        : public std::true_type {};
-template<> struct utils::EnableBitMaskOperators<filament::backend::MapBufferAccessFlags>
-        : public std::true_type {};
-
 template<> struct utils::EnableIntegerOperators<filament::backend::TextureCubemapFace>
        : public std::true_type {};
 template<> struct utils::EnableIntegerOperators<filament::backend::FeatureLevel>
@@ -45,7 +45,6 @@ struct HwVertexBufferInfo;
 struct HwVertexBuffer;
 struct HwDescriptorSetLayout;
 struct HwDescriptorSet;
-struct HwMemoryMappedBuffer;

 /*
 * A handle to a backend resource. HandleBase is for internal use only.
@@ -160,7 +159,6 @@ using VertexBufferHandle        = Handle<HwVertexBuffer>;
 using VertexBufferInfoHandle    = Handle<HwVertexBufferInfo>;
 using DescriptorSetLayoutHandle = Handle<HwDescriptorSetLayout>;
 using DescriptorSetHandle       = Handle<HwDescriptorSet>;
-using MemoryMappedBufferHandle  = Handle<HwMemoryMappedBuffer>;

 } // namespace filament::backend

@@ -168,7 +168,6 @@ protected:
    EGLConfig mEGLConfig = EGL_NO_CONFIG_KHR;
    Config mContextAttribs;
    std::vector<EGLContext> mAdditionalContexts;
-    bool mMSAA4XSupport = false;

    // supported extensions detected at runtime
    struct {
@@ -219,8 +218,6 @@ private:
            return makeCurrent(mCurrentContext, drawSurface, readSurface);
        }
    } egl{ mEGLDisplay };
-
-    bool checkIfMSAASwapChainSupported(uint32_t samples) const noexcept;
 };

 } // namespace filament::backend
@@ -27,7 +27,6 @@
 #include <backend/AcquiredImage.h>

 #include <utils/CString.h>
-#include <utils/FixedCapacityVector.h>
 #include <utils/compiler.h>

 #include <functional>
@@ -72,11 +71,7 @@ public:

    virtual ShaderModel getShaderModel() const noexcept = 0;

-    // The shader languages used for shaders for this driver in order of preference, used to inform
-    // matdbg.
-    //
-    // The `preferredLanguage` is only a hint. If the backend supports it, it will appear first in
-    // the list.
+    // The shader language used for shaders for this driver, used to inform matdbg.
    //
    // For OpenGL, this distinguishes whether the driver's shaders are powered by ESSL1 or ESSL3.
    // This information is used by matdbg to display the correct shader code to the web UI and patch
@@ -84,8 +79,7 @@ public:
    //
    // Metal shaders can either be MSL or Metal libraries, but at time of writing, matdbg can only
    // interface with MSL.
-    virtual utils::FixedCapacityVector<ShaderLanguage> getShaderLanguages(
-            ShaderLanguage preferredLanguage) const noexcept = 0;
+    virtual ShaderLanguage getShaderLanguage() const noexcept = 0;

    // Returns the dispatcher. This is only called once during initialization of the CommandStream,
    // so it doesn't matter that it's virtual.
@@ -108,16 +108,12 @@
    DECL_DRIVER_API_RETURN(R, N, PAIR_ARGS_N(ARG, ##__VA_ARGS__), PAIR_ARGS_N(PARAM, ##__VA_ARGS__))

 #define DECL_DRIVER_API_TAGGED_R_N(R, N, ...) \
-    DECL_DRIVER_API_RETURN(R, N, PAIR_ARGS_N(ARG, ##__VA_ARGS__, utils::CString&&, tag = {}), \
-            PAIR_ARGS_N(PARAM, ##__VA_ARGS__, utils::CString&&, tag))
+    DECL_DRIVER_API_RETURN(R, N, PAIR_ARGS_N(ARG, ##__VA_ARGS__, utils::CString, tag = {}), \
+            PAIR_ARGS_N(PARAM, ##__VA_ARGS__, utils::CString, tag))

 #define DECL_DRIVER_API_SYNCHRONOUS_N(R, N, ...) \
    DECL_DRIVER_API_SYNCHRONOUS(R, N, PAIR_ARGS_N(ARG, ##__VA_ARGS__), PAIR_ARGS_N(PARAM, ##__VA_ARGS__))

-#define DECL_DRIVER_API_SYNCHRONOUS_TAGGED_N(R, N, ...) \
-    DECL_DRIVER_API_SYNCHRONOUS(R, N, PAIR_ARGS_N(ARG, ##__VA_ARGS__, utils::CString, tag = {}), \
-            PAIR_ARGS_N(PARAM, ##__VA_ARGS__, utils::CString, tag))
-
 // on some compilers the ##__VA_ARGS__ hack is not supported, so we can't handle 0-parameter APIs
 // with DECL_DRIVER_API_SYNCHRONOUS_N
 #define DECL_DRIVER_API_SYNCHRONOUS_0(R, N) \
@@ -295,11 +291,27 @@ DECL_DRIVER_API_TAGGED_R_N(backend::DescriptorSetLayoutHandle, createDescriptorS
 DECL_DRIVER_API_TAGGED_R_N(backend::DescriptorSetHandle, createDescriptorSet,
        backend::DescriptorSetLayoutHandle, dslh)

-DECL_DRIVER_API_TAGGED_R_N(backend::MemoryMappedBufferHandle, mapBuffer,
+DECL_DRIVER_API_N(updateDescriptorSetBuffer,
+        backend::DescriptorSetHandle, dsh,
+        backend::descriptor_binding_t, binding,
        backend::BufferObjectHandle, boh,
-        size_t, offset,
-        size_t, size,
-        backend::MapBufferAccessFlags, access)
+        uint32_t, offset,
+        uint32_t, size
+)
+
+DECL_DRIVER_API_N(updateDescriptorSetTexture,
+        backend::DescriptorSetHandle, dsh,
+        backend::descriptor_binding_t, binding,
+        backend::TextureHandle, th,
+        SamplerParams, params
+)
+
+DECL_DRIVER_API_N(bindDescriptorSet,
+        backend::DescriptorSetHandle, dsh,
+        backend::descriptor_set_t, set,
+        backend::DescriptorSetOffsetArray&&, offsets
+)
+

 /*
 * Destroying driver objects
@@ -309,7 +321,7 @@ DECL_DRIVER_API_TAGGED_R_N(backend::MemoryMappedBufferHandle, mapBuffer,
 DECL_DRIVER_API_N(destroyVertexBuffer,          backend::VertexBufferHandle, vbh)
 DECL_DRIVER_API_N(destroyVertexBufferInfo,      backend::VertexBufferInfoHandle, vbih)
 DECL_DRIVER_API_N(destroyIndexBuffer,           backend::IndexBufferHandle, ibh)
-DECL_DRIVER_API_N(destroyBufferObject,          backend::BufferObjectHandle, boh)
+DECL_DRIVER_API_N(destroyBufferObject,          backend::BufferObjectHandle, ibh)
 DECL_DRIVER_API_N(destroyRenderPrimitive,       backend::RenderPrimitiveHandle, rph)
 DECL_DRIVER_API_N(destroyProgram,               backend::ProgramHandle, ph)
 DECL_DRIVER_API_N(destroyTexture,               backend::TextureHandle, th)
@@ -321,7 +333,6 @@ DECL_DRIVER_API_N(destroyFence,                 backend::FenceHandle, fh)
 DECL_DRIVER_API_N(destroySync,                  backend::SyncHandle, sh)
 DECL_DRIVER_API_N(destroyDescriptorSetLayout,   backend::DescriptorSetLayoutHandle, dslh)
 DECL_DRIVER_API_N(destroyDescriptorSet,         backend::DescriptorSetHandle, dsh)
-DECL_DRIVER_API_N(unmapBuffer,                  backend::MemoryMappedBufferHandle, mmbh)

 /*
 * Synchronous APIs
@@ -329,14 +340,13 @@ DECL_DRIVER_API_N(unmapBuffer,                  backend::MemoryMappedBufferHandl
 */

 DECL_DRIVER_API_SYNCHRONOUS_0(void, terminate)
-DECL_DRIVER_API_SYNCHRONOUS_TAGGED_N(backend::StreamHandle, createStreamNative, void*, stream)
-DECL_DRIVER_API_SYNCHRONOUS_TAGGED_N(backend::StreamHandle, createStreamAcquired)
+DECL_DRIVER_API_SYNCHRONOUS_N(backend::StreamHandle, createStreamNative, void*, stream, utils::CString, tag)
+DECL_DRIVER_API_SYNCHRONOUS_N(backend::StreamHandle, createStreamAcquired, utils::CString, tag)
 DECL_DRIVER_API_SYNCHRONOUS_N(void, setAcquiredImage, backend::StreamHandle, stream, void*, image, const math::mat3f&, transform, backend::CallbackHandler*, handler, backend::StreamCallback, cb, void*, userData)
 DECL_DRIVER_API_SYNCHRONOUS_N(void, setStreamDimensions, backend::StreamHandle, stream, uint32_t, width, uint32_t, height)
 DECL_DRIVER_API_SYNCHRONOUS_N(int64_t, getStreamTimestamp, backend::StreamHandle, stream)
 DECL_DRIVER_API_SYNCHRONOUS_N(void, updateStreams, backend::DriverApi*, driver)
 DECL_DRIVER_API_SYNCHRONOUS_N(backend::FenceStatus, getFenceStatus, backend::FenceHandle, fh)
-DECL_DRIVER_API_SYNCHRONOUS_N(backend::FenceStatus, fenceWait, backend::FenceHandle, fh, uint64_t, timeout)
 DECL_DRIVER_API_SYNCHRONOUS_N(void, getPlatformSync, backend::SyncHandle, sh,
        backend::CallbackHandler*, handler, backend::Platform::SyncCallback, cb, void*, userData)
 DECL_DRIVER_API_SYNCHRONOUS_N(bool, isTextureFormatSupported, backend::TextureFormat, format)
@@ -363,7 +373,7 @@ DECL_DRIVER_API_SYNCHRONOUS_0(size_t, getMaxArrayTextureLayers)
 DECL_DRIVER_API_SYNCHRONOUS_0(math::float2, getClipSpaceParams)
 DECL_DRIVER_API_SYNCHRONOUS_N(void, setupExternalImage2, backend::Platform::ExternalImageHandleRef, image)
 DECL_DRIVER_API_SYNCHRONOUS_N(void, setupExternalImage, void*, image)
-DECL_DRIVER_API_SYNCHRONOUS_N(backend::TimerQueryResult, getTimerQueryValue, backend::TimerQueryHandle, tqh, uint64_t*, elapsedTime)
+DECL_DRIVER_API_SYNCHRONOUS_N(backend::TimerQueryResult, getTimerQueryValue, backend::TimerQueryHandle, query, uint64_t*, elapsedTime)
 DECL_DRIVER_API_SYNCHRONOUS_N(bool, isWorkaroundNeeded, backend::Workaround, workaround)
 DECL_DRIVER_API_SYNCHRONOUS_0(backend::FeatureLevel, getFeatureLevel)

@@ -388,16 +398,16 @@ DECL_DRIVER_API_N(updateBufferObject,
        uint32_t, byteOffset)

 DECL_DRIVER_API_N(registerBufferObjectStreams,
-        backend::BufferObjectHandle, boh,
+        backend::BufferObjectHandle, ibh,
        backend::BufferObjectStreamDescriptor&&, streams)

 DECL_DRIVER_API_N(updateBufferObjectUnsynchronized,
-        backend::BufferObjectHandle, boh,
+        backend::BufferObjectHandle, ibh,
        backend::BufferDescriptor&&, data,
        uint32_t, byteOffset)

 DECL_DRIVER_API_N(resetBufferObject,
-        backend::BufferObjectHandle, boh)
+        backend::BufferObjectHandle, ibh)

 DECL_DRIVER_API_N(update3DImage,
        backend::TextureHandle, th,
@@ -426,10 +436,10 @@ DECL_DRIVER_API_0(endRenderPass)
 DECL_DRIVER_API_0(nextSubpass)

 DECL_DRIVER_API_N(beginTimerQuery,
-        backend::TimerQueryHandle, tqh)
+        backend::TimerQueryHandle, query)

 DECL_DRIVER_API_N(endTimerQuery,
-        backend::TimerQueryHandle, tqh)
+        backend::TimerQueryHandle, query)

 DECL_DRIVER_API_N(compilePrograms,
        backend::CompilerPriorityQueue, priority,
@@ -437,26 +447,6 @@ DECL_DRIVER_API_N(compilePrograms,
        backend::CallbackHandler::Callback, callback,
        void*, user)

-DECL_DRIVER_API_N(updateDescriptorSetBuffer,
-        backend::DescriptorSetHandle, dsh,
-        backend::descriptor_binding_t, binding,
-        backend::BufferObjectHandle, boh,
-        uint32_t, offset,
-        uint32_t, size
-)
-
-DECL_DRIVER_API_N(updateDescriptorSetTexture,
-        backend::DescriptorSetHandle, dsh,
-        backend::descriptor_binding_t, binding,
-        backend::TextureHandle, th,
-        SamplerParams, params
-)
-
-DECL_DRIVER_API_N(copyToMemoryMappedBuffer,
-        backend::MemoryMappedBufferHandle, mmbh,
-        size_t, offset,
-        backend::BufferDescriptor&&, data)
-
 /*
 * Swap chain
 */
@@ -545,12 +535,6 @@ DECL_DRIVER_API_N(bindPipeline,
 DECL_DRIVER_API_N(bindRenderPrimitive,
        backend::RenderPrimitiveHandle, rph)

-DECL_DRIVER_API_N(bindDescriptorSet,
-        backend::DescriptorSetHandle, dsh,
-        backend::descriptor_set_t, set,
-        backend::DescriptorSetOffsetArray&&, offsets
-)
-
 DECL_DRIVER_API_N(draw2,
        uint32_t, indexOffset,
        uint32_t, indexCount,
@@ -18,16 +18,10 @@

 #include "DataReshaper.h"

-#include <backend/PixelBufferDescriptor.h>
 #include <backend/DriverEnums.h>

-#include <utils/BitmaskEnum.h>
-#include <utils/compiler.h>
 #include <utils/CString.h>

-#include <cstddef>
-#include <cstdint>
-#include <utility>
 #include <string_view>

 namespace filament::backend {
@@ -642,7 +636,7 @@ bool reshape(const PixelBufferDescriptor& data, PixelBufferDescriptor& reshaped)
    switch (data.type) {
        case PixelDataType::BYTE:
        case PixelDataType::UBYTE: {
-            uint8_t* bytes = static_cast<uint8_t*>(malloc(reshapedSize));
+            uint8_t* bytes = (uint8_t*) malloc(reshapedSize);
            DataReshaper::reshape<uint8_t, 3, 4>(bytes, data.buffer, data.size);
            PixelBufferDescriptor pbd(bytes, reshapedSize, reshapedFormat, data.type,
                    data.alignment, data.left, data.top, data.stride, freeFunc);
@@ -652,7 +646,7 @@ bool reshape(const PixelBufferDescriptor& data, PixelBufferDescriptor& reshaped)
        case PixelDataType::SHORT:
        case PixelDataType::USHORT:
        case PixelDataType::HALF: {
-            uint8_t* bytes = static_cast<uint8_t*>(malloc(reshapedSize));
+            uint8_t* bytes = (uint8_t*) malloc(reshapedSize);
            DataReshaper::reshape<uint16_t, 3, 4>(bytes, data.buffer, data.size);
            PixelBufferDescriptor pbd(bytes, reshapedSize, reshapedFormat, data.type,
                    data.alignment, data.left, data.top, data.stride, freeFunc);
@@ -661,7 +655,7 @@ bool reshape(const PixelBufferDescriptor& data, PixelBufferDescriptor& reshaped)
        }
        case PixelDataType::INT:
        case PixelDataType::UINT: {
-            uint8_t* bytes = static_cast<uint8_t*>(malloc(reshapedSize));
+            uint8_t* bytes = (uint8_t*) malloc(reshapedSize);
            DataReshaper::reshape<uint32_t, 3, 4>(bytes, data.buffer, data.size);
            PixelBufferDescriptor pbd(bytes, reshapedSize, reshapedFormat, data.type,
                    data.alignment, data.left, data.top, data.stride, freeFunc);
@@ -669,7 +663,7 @@ bool reshape(const PixelBufferDescriptor& data, PixelBufferDescriptor& reshaped)
            return true;
        }
        case PixelDataType::FLOAT: {
-            uint8_t* bytes = static_cast<uint8_t*>(malloc(reshapedSize));
+            uint8_t* bytes = (uint8_t*) malloc(reshapedSize);
            DataReshaper::reshape<float, 3, 4>(bytes, data.buffer, data.size);
            PixelBufferDescriptor pbd(bytes, reshapedSize, reshapedFormat, data.type,
                    data.alignment, data.left, data.top, data.stride, freeFunc);
@@ -63,7 +63,6 @@ public:
    static void copyImage(uint8_t* UTILS_RESTRICT dest,
                          const uint8_t* UTILS_RESTRICT src,
                          size_t srcBytesPerRow, size_t /*srcChannelCount*/,
-                          size_t /*dstRowOffset */, size_t /*dstColumnOffset */,
                          size_t dstBytesPerRow, size_t /*dstChannelCount*/,
                          size_t /*width*/, size_t height, bool /*swizzle*/) {
        if (srcBytesPerRow == dstBytesPerRow) {
@@ -80,20 +79,17 @@ public:
    template<typename dstComponentType, typename srcComponentType>
    static void reshapeImage(uint8_t* UTILS_RESTRICT dest, const uint8_t* UTILS_RESTRICT src,
            size_t srcBytesPerRow,
-            size_t srcChannelCount,
-            size_t dstRowOffset, size_t dstColumnOffset,
-            size_t dstBytesPerRow, size_t dstChannelCount,
+            size_t srcChannelCount, size_t dstBytesPerRow, size_t dstChannelCount,
            size_t width, size_t height, bool swizzle) {
        const dstComponentType dstMaxValue = getMaxValue<dstComponentType>();
        const srcComponentType srcMaxValue = getMaxValue<srcComponentType>();
        const size_t minChannelCount = math::min(srcChannelCount, dstChannelCount);
        assert_invariant(minChannelCount <= 4);
        UTILS_ASSUME(minChannelCount <= 4);
-        dest += (dstRowOffset * dstBytesPerRow);
        const int inds[4] = { swizzle ? 2 : 0, 1, swizzle ? 0 : 2, 3 };
        for (size_t row = 0; row < height; ++row) {
-            const srcComponentType* in = (const srcComponentType*) src;
-            dstComponentType* out = (dstComponentType*)dest + (dstColumnOffset * dstChannelCount);
+            const srcComponentType* in = (const srcComponentType*)src;
+            dstComponentType* out = (dstComponentType*)dest;
            for (size_t column = 0; column < width; ++column) {
                for (size_t channel = 0; channel < minChannelCount; ++channel) {
                    if constexpr (std::is_same_v<dstComponentType, srcComponentType>) {
@@ -132,23 +128,17 @@ public:
            default: return false;
        }
        void (*reshaper)(uint8_t* dest, const uint8_t* src, size_t srcBytesPerRow,
-                size_t srcChannelCount,
-                size_t srcRowOffset, size_t srcColumnOffset,
-                size_t dstBytesPerRow, size_t dstChannelCount,
+                size_t srcChannelCount, size_t dstBytesPerRow, size_t dstChannelCount,
                size_t width, size_t height, bool swizzle) = nullptr;
-        constexpr auto UBYTE = PixelDataType::UBYTE;
-        constexpr auto FLOAT = PixelDataType::FLOAT;
-        constexpr auto UINT = PixelDataType::UINT;
-        constexpr auto INT = PixelDataType::INT;
-        constexpr auto HALF = PixelDataType::HALF;
+        constexpr auto UBYTE = PixelDataType::UBYTE, FLOAT = PixelDataType::FLOAT,
+                UINT = PixelDataType::UINT, INT = PixelDataType::INT;
        switch (dst->type) {
            case UBYTE:
                switch (srcType) {
                    case UBYTE:
                        reshaper = reshapeImage<uint8_t, uint8_t>;
                        if (dst->format == PixelDataFormat::RGBA &&
-                                dstChannelCount == srcChannelCount && !swizzle && dst->top == 0 &&
-                                dst->left == 0) {
+                                dstChannelCount == srcChannelCount && !swizzle) {
                            reshaper = copyImage;
                        }
                        break;
@@ -185,20 +175,13 @@ public:
                    default: return false;
                }
                break;
-            case HALF:
-                switch (srcType) {
-                    case HALF: reshaper = copyImage; break;
-                    default: return false;
-                }
-                break;
            default:
                return false;
        }
        uint8_t* dstBytes = (uint8_t*) dst->buffer;
        const int dstBytesPerRow = PixelBufferDescriptor::computeDataSize(dst->format, dst->type,
                dst->stride ? dst->stride : width, 1, dst->alignment);
-        reshaper(dstBytes, srcBytes, srcBytesPerRow, srcChannelCount,
-                dst->top, dst->left, dstBytesPerRow,
+        reshaper(dstBytes, srcBytes, srcBytesPerRow, srcChannelCount, dstBytesPerRow,
                dstChannelCount, width, height, swizzle);
        return true;
    }
@@ -78,9 +78,6 @@ struct HwBufferObject : public HwBase {
    explicit HwBufferObject(uint32_t byteCount) noexcept : byteCount(byteCount) {}
 };

-struct HwMemoryMappedBuffer : public HwBase {
-};
-
 struct HwIndexBuffer : public HwBase {
    uint32_t count : 27;
    uint32_t elementSize : 5;
@@ -214,7 +211,7 @@ public:
 protected:
    class CallbackDataDetails;

-    void scheduleDestroy(BufferDescriptor&& buffer) noexcept {
+    inline void scheduleDestroy(BufferDescriptor&& buffer) noexcept {
        if (buffer.hasCallback()) {
            scheduleDestroySlow(std::move(buffer));
        }
@@ -18,7 +18,6 @@
 #define TNT_FILAMENT_DRIVER_METALBUFFER_H

 #include "MetalContext.h"
-#include "MetalFlags.h"

 #include <backend/DriverEnums.h>
 #include <backend/platforms/PlatformMetal.h>
@@ -154,7 +153,7 @@ private:
    Type mType = Type::NONE;

    static PlatformMetal* platform;
-    static std::array<uint64_t, TypeCount> aliveBuffers;
+    static std::array<std::atomic<uint64_t>, TypeCount> aliveBuffers;
 };

 class MetalBuffer {
@@ -192,15 +191,6 @@ public:

    void* getCpuBuffer() const noexcept { return mCpuBuffer; }

-    void setLabel(const utils::CString& label) {
-#if FILAMENT_METAL_DEBUG_LABELS
-        if (label.empty()) {
-            return;
-        }
-        mBuffer.get().label = @(label.c_str_safe());
-#endif
-    }
-
    enum Stage : uint8_t {
        VERTEX      = 1u << 0u,
        FRAGMENT    = 1u << 1u,
@@ -24,7 +24,7 @@
 namespace filament {
 namespace backend {

-std::array<uint64_t, TrackedMetalBuffer::TypeCount> TrackedMetalBuffer::aliveBuffers = { 0 };
+std::array<std::atomic<uint64_t>, TrackedMetalBuffer::TypeCount> TrackedMetalBuffer::aliveBuffers = { 0 };
 PlatformMetal* TrackedMetalBuffer::platform = nullptr;
 PlatformMetal* ScopedAllocationTimer::platform = nullptr;

@@ -102,7 +102,7 @@ id<MTLCommandBuffer> getPendingCommandBuffer(MetalContext* context) {
    context->pendingCommandBuffer = [context->commandQueue commandBuffer];
    // It's safe for this block to capture the context variable. MetalDriver::terminate will ensure
    // all frames and their completion handlers finish before context is deallocated.
-    const uint64_t thisCommandBufferId = context->pendingCommandBufferId;
+    uint64_t thisCommandBufferId = context->pendingCommandBufferId;
    [context->pendingCommandBuffer addCompletedHandler:^(id <MTLCommandBuffer> buffer) {
        context->resourceTracker.clearResources((__bridge void*) buffer);

@@ -118,11 +118,6 @@ id<MTLCommandBuffer> getPendingCommandBuffer(MetalContext* context) {
                context->memorylessLimitsReached = true;
            }
        }
-
-        if (UTILS_UNLIKELY(errorCode != MTLCommandBufferErrorNone)) {
-            LOG(ERROR) << "Filament Metal command buffer errored with code: " << errorCode << " ("
-                       << stringifyMTLCommandBufferError(errorCode) << ").";
-        }
    }];
    FILAMENT_CHECK_POSTCONDITION(context->pendingCommandBuffer)
            << "Could not obtain command buffer.";
@@ -25,9 +25,8 @@

 #include <backend/SamplerDescriptor.h>

-#include <utils/FixedCapacityVector.h>
-#include <utils/Log.h>
 #include <utils/compiler.h>
+#include <utils/Log.h>
 #include <utils/debug.h>

 #include <functional>
@@ -70,8 +69,7 @@ private:
    MetalContext* mContext;

    ShaderModel getShaderModel() const noexcept final;
-    utils::FixedCapacityVector<ShaderLanguage> getShaderLanguages(
-            ShaderLanguage preferredLanguage) const noexcept final;
+    ShaderLanguage getShaderLanguage() const noexcept final;

    // Overrides the default implementation by wrapping the call to fn in an @autoreleasepool block.
    void execute(std::function<void(void)> const& fn) noexcept final;
@@ -418,14 +418,14 @@ void MetalDriver::finish(int) {
 }

 void MetalDriver::createVertexBufferInfoR(Handle<HwVertexBufferInfo> vbih, uint8_t bufferCount,
-        uint8_t attributeCount, AttributeArray attributes, utils::CString&& tag) {
+        uint8_t attributeCount, AttributeArray attributes, utils::CString tag) {
    construct_handle<MetalVertexBufferInfo>(vbih, *mContext,
            bufferCount, attributeCount, attributes);
    mHandleAllocator.associateTagToHandle(vbih.getId(), std::move(tag));
 }

 void MetalDriver::createVertexBufferR(Handle<HwVertexBuffer> vbh,
-        uint32_t vertexCount, Handle<HwVertexBufferInfo> vbih, utils::CString&& tag) {
+        uint32_t vertexCount, Handle<HwVertexBufferInfo> vbih, utils::CString tag) {
    MetalVertexBufferInfo const* const vbi = handle_cast<const MetalVertexBufferInfo>(vbih);
    construct_handle<MetalVertexBuffer>(vbh, *mContext, vertexCount, vbi->bufferCount, vbih);
    mHandleAllocator.associateTagToHandle(vbh.getId(), std::move(tag));
@@ -433,7 +433,7 @@ void MetalDriver::createVertexBufferR(Handle<HwVertexBuffer> vbh,
 }

 void MetalDriver::createIndexBufferR(Handle<HwIndexBuffer> ibh, ElementType elementType,
-        uint32_t indexCount, BufferUsage usage, utils::CString&& tag) {
+        uint32_t indexCount, BufferUsage usage, utils::CString tag) {
    auto elementSize = (uint8_t)getElementTypeSize(elementType);
    auto* indexBuffer =
            construct_handle<MetalIndexBuffer>(ibh, *mContext, usage, elementSize, indexCount);
@@ -441,18 +441,16 @@ void MetalDriver::createIndexBufferR(Handle<HwIndexBuffer> ibh, ElementType elem
    FILAMENT_CHECK_POSTCONDITION(buffer.wasAllocationSuccessful())
            << "Could not allocate Metal index buffer of size " << buffer.getSize()
            << ", tag=" << tag.c_str_safe();
-    buffer.setLabel(tag);
    mHandleAllocator.associateTagToHandle(ibh.getId(), std::move(tag));
 }

 void MetalDriver::createBufferObjectR(Handle<HwBufferObject> boh, uint32_t byteCount,
-        BufferObjectBinding bindingType, BufferUsage usage, utils::CString&& tag) {
+        BufferObjectBinding bindingType, BufferUsage usage, utils::CString tag) {
    auto* bufferObject =
            construct_handle<MetalBufferObject>(boh, *mContext, bindingType, usage, byteCount);
    FILAMENT_CHECK_POSTCONDITION(bufferObject->getBuffer()->wasAllocationSuccessful())
            << "Could not allocate Metal buffer of size " << byteCount
            << ", tag=" << tag.c_str_safe();
-    bufferObject->getBuffer()->setLabel(tag);
    mHandleAllocator.associateTagToHandle(boh.getId(), std::move(tag));
 }

@@ -488,16 +486,13 @@ inline const char* stringify(SamplerType samplerType) {

 void MetalDriver::createTextureR(Handle<HwTexture> th, SamplerType target, uint8_t levels,
        TextureFormat format, uint8_t samples, uint32_t width, uint32_t height,
-        uint32_t depth, TextureUsage usage, utils::CString&& tag) {
+        uint32_t depth, TextureUsage usage, utils::CString tag) {
    // Clamp sample count to what the device supports.
    auto& sc = mContext->sampleCountLookup;
    samples = sc[std::min(MAX_SAMPLE_COUNT, samples)];

-    MetalTexture* texture = construct_handle<MetalTexture>(th, *mContext, target, levels, format,
-            samples, width, height, depth, usage);
-    mContext->textures.insert(texture);
-
-    texture->setLabel(tag);
+    mContext->textures.insert(construct_handle<MetalTexture>(
+            th, *mContext, target, levels, format, samples, width, height, depth, usage));

    DEBUG_LOG(
            "createTextureR(th = %d, target = %s, levels = %d, format = ?, samples = %d, width = "
@@ -508,22 +503,18 @@ void MetalDriver::createTextureR(Handle<HwTexture> th, SamplerType target, uint8
 }

 void MetalDriver::createTextureViewR(Handle<HwTexture> th, Handle<HwTexture> srch,
-        uint8_t baseLevel, uint8_t levelCount, utils::CString&& tag) {
+        uint8_t baseLevel, uint8_t levelCount, utils::CString tag) {
    MetalTexture const* src = handle_cast<MetalTexture>(srch);
-    MetalTexture* texture =
-            construct_handle<MetalTexture>(th, *mContext, src, baseLevel, levelCount);
-    mContext->textures.insert(texture);
-    texture->setLabel(tag);
+    mContext->textures.insert(
+            construct_handle<MetalTexture>(th, *mContext, src, baseLevel, levelCount));
    mHandleAllocator.associateTagToHandle(th.getId(), std::move(tag));
 }

 void MetalDriver::createTextureViewSwizzleR(Handle<HwTexture> th, Handle<HwTexture> srch,
        backend::TextureSwizzle r, backend::TextureSwizzle g, backend::TextureSwizzle b,
-        backend::TextureSwizzle a, utils::CString&& tag) {
+        backend::TextureSwizzle a, utils::CString tag) {
    MetalTexture const* src = handle_cast<MetalTexture>(srch);
-    MetalTexture* texture = construct_handle<MetalTexture>(th, *mContext, src, r, g, b, a);
-    mContext->textures.insert(texture);
-    texture->setLabel(tag);
+    mContext->textures.insert(construct_handle<MetalTexture>(th, *mContext, src, r, g, b, a));
    mHandleAllocator.associateTagToHandle(th.getId(), std::move(tag));
 }

@@ -531,17 +522,15 @@ void MetalDriver::createTextureExternalImage2R(Handle<HwTexture> th,
        backend::SamplerType target,
        backend::TextureFormat format,
        uint32_t width, uint32_t height, backend::TextureUsage usage,
-        Platform::ExternalImageHandleRef image, utils::CString&& tag) {
+        Platform::ExternalImageHandleRef image, utils::CString tag) {
    // FIXME: implement createTextureExternalImage2R
 }

 void MetalDriver::createTextureExternalImageR(Handle<HwTexture> th, backend::SamplerType target,
        backend::TextureFormat format, uint32_t width, uint32_t height, backend::TextureUsage usage,
-        void* image, utils::CString&& tag) {
-    MetalTexture* texture = construct_handle<MetalTexture>(th, *mContext, format, width, height,
-            usage, (CVPixelBufferRef) image);
-    mContext->textures.insert(texture);
-    texture->setLabel(tag);
+        void* image, utils::CString tag) {
+    mContext->textures.insert(construct_handle<MetalTexture>(
+            th, *mContext, format, width, height, usage, (CVPixelBufferRef)image));
    // This release matches the retain call in setupExternalImage. The MetalTexture will have
    // retained the buffer by now.
    CVPixelBufferRelease((CVPixelBufferRef)image);
@@ -550,11 +539,9 @@ void MetalDriver::createTextureExternalImageR(Handle<HwTexture> th, backend::Sam

 void MetalDriver::createTextureExternalImagePlaneR(Handle<HwTexture> th,
        backend::TextureFormat format, uint32_t width, uint32_t height, backend::TextureUsage usage,
-        void* image, uint32_t plane, utils::CString&& tag) {
-    MetalTexture* texture = construct_handle<MetalTexture>(th, *mContext, format, width, height,
-            usage, (CVPixelBufferRef) image, plane);
-    mContext->textures.insert(texture);
-    texture->setLabel(tag);
+        void* image, uint32_t plane, utils::CString tag) {
+    mContext->textures.insert(construct_handle<MetalTexture>(
+            th, *mContext, format, width, height, usage, (CVPixelBufferRef)image, plane));
    // This release matches the retain call in setupExternalImage. The MetalTexture will have
    // retained the buffer by now.
    CVPixelBufferRelease((CVPixelBufferRef)image);
@@ -564,7 +551,7 @@ void MetalDriver::createTextureExternalImagePlaneR(Handle<HwTexture> th,
 void MetalDriver::importTextureR(Handle<HwTexture> th, intptr_t i,
        SamplerType target, uint8_t levels,
        TextureFormat format, uint8_t samples, uint32_t width, uint32_t height,
-        uint32_t depth, TextureUsage usage, utils::CString&& tag) {
+        uint32_t depth, TextureUsage usage, utils::CString tag) {
    id<MTLTexture> metalTexture = (id<MTLTexture>) CFBridgingRelease((void*) i);
    FILAMENT_CHECK_PRECONDITION(metalTexture.width == width)
            << "Imported id<MTLTexture> width (" << metalTexture.width
@@ -579,22 +566,20 @@ void MetalDriver::importTextureR(Handle<HwTexture> th, intptr_t i,
    FILAMENT_CHECK_PRECONDITION(metalTexture.textureType == filamentMetalType)
            << "Imported id<MTLTexture> type (" << metalTexture.textureType
            << ") != Filament texture type (" << filamentMetalType << ")";
-    MetalTexture* texture = construct_handle<MetalTexture>(th, *mContext, target, levels, format,
-            samples, width, height, depth, usage, metalTexture);
-    mContext->textures.insert(texture);
-    texture->setLabel(tag);
+    mContext->textures.insert(construct_handle<MetalTexture>(th, *mContext,
+        target, levels, format, samples, width, height, depth, usage, metalTexture));
    mHandleAllocator.associateTagToHandle(th.getId(), std::move(tag));
 }

 void MetalDriver::createRenderPrimitiveR(Handle<HwRenderPrimitive> rph,
        Handle<HwVertexBuffer> vbh, Handle<HwIndexBuffer> ibh,
-        PrimitiveType pt, utils::CString&& tag) {
+        PrimitiveType pt, utils::CString tag) {
    construct_handle<MetalRenderPrimitive>(rph);
    MetalDriver::setRenderPrimitiveBuffer(rph, pt, vbh, ibh);
    mHandleAllocator.associateTagToHandle(rph.getId(), std::move(tag));
 }

-void MetalDriver::createProgramR(Handle<HwProgram> rph, Program&& program, utils::CString&& tag) {
+void MetalDriver::createProgramR(Handle<HwProgram> rph, Program&& program, utils::CString tag) {
 #if FILAMENT_METAL_DEBUG_LOG
    auto handleId = rph.getId();
    DEBUG_LOG("createProgramR(rph = %d, program = ", handleId);
@@ -604,7 +589,7 @@ void MetalDriver::createProgramR(Handle<HwProgram> rph, Program&& program, utils
    mHandleAllocator.associateTagToHandle(rph.getId(), std::move(tag));
 }

-void MetalDriver::createDefaultRenderTargetR(Handle<HwRenderTarget> rth, utils::CString&& tag) {
+void MetalDriver::createDefaultRenderTargetR(Handle<HwRenderTarget> rth, utils::CString tag) {
    construct_handle<MetalRenderTarget>(rth, mContext);
    mHandleAllocator.associateTagToHandle(rth.getId(), std::move(tag));
 }
@@ -612,7 +597,7 @@ void MetalDriver::createDefaultRenderTargetR(Handle<HwRenderTarget> rth, utils::
 void MetalDriver::createRenderTargetR(Handle<HwRenderTarget> rth,
        TargetBufferFlags targetBufferFlags, uint32_t width, uint32_t height,
        uint8_t samples, uint8_t layerCount, MRT color,
-        TargetBufferInfo depth, TargetBufferInfo stencil, utils::CString&& tag) {
+        TargetBufferInfo depth, TargetBufferInfo stencil, utils::CString tag) {
    FILAMENT_CHECK_PRECONDITION(!isInRenderPass(mContext))
            << "createRenderTarget must be called outside of a render pass.";
    // Clamp sample count to what the device supports.
@@ -659,14 +644,14 @@ void MetalDriver::createRenderTargetR(Handle<HwRenderTarget> rth,
    mHandleAllocator.associateTagToHandle(rth.getId(), std::move(tag));
 }

-void MetalDriver::createFenceR(Handle<HwFence> fh, utils::CString&& tag) {
+void MetalDriver::createFenceR(Handle<HwFence> fh, utils::CString tag) {
    auto* fence = handle_cast<MetalFence>(fh);
    fence->encode();
    mHandleAllocator.associateTagToHandle(fh.getId(), std::move(tag));
 }

 void MetalDriver::createSwapChainR(Handle<HwSwapChain> sch, void* nativeWindow, uint64_t flags,
-        utils::CString&& tag) {
+        utils::CString tag) {
    // TODO: support MSAA swapchain

    if (UTILS_UNLIKELY(flags & SWAP_CHAIN_CONFIG_APPLE_CVPIXELBUFFER)) {
@@ -683,18 +668,18 @@ void MetalDriver::createSwapChainR(Handle<HwSwapChain> sch, void* nativeWindow,
 }

 void MetalDriver::createSwapChainHeadlessR(Handle<HwSwapChain> sch,
-        uint32_t width, uint32_t height, uint64_t flags, utils::CString&& tag) {
+        uint32_t width, uint32_t height, uint64_t flags, utils::CString tag) {
    construct_handle<MetalSwapChain>(sch, *mContext, mPlatform, width, height, flags);
    mHandleAllocator.associateTagToHandle(sch.getId(), std::move(tag));
 }

-void MetalDriver::createSyncR(Handle<HwSync> sh, utils::CString&& tag) {
+void MetalDriver::createSyncR(Handle<HwSync> sh, utils::CString tag) {
    // TODO: Ensure sync is active, and then invoke and clear all pending
    // callbacks.
    mHandleAllocator.associateTagToHandle(sh.getId(), std::move(tag));
 }

-void MetalDriver::createTimerQueryR(Handle<HwTimerQuery> tqh, utils::CString&& tag) {
+void MetalDriver::createTimerQueryR(Handle<HwTimerQuery> tqh, utils::CString tag) {
    // nothing to do, timer query was constructed in createTimerQueryS
    mHandleAllocator.associateTagToHandle(tqh.getId(), std::move(tag));
 }
@@ -733,7 +718,7 @@ const char* toString(DescriptorFlags flags) {
 }

 void MetalDriver::createDescriptorSetLayoutR(
-        Handle<HwDescriptorSetLayout> dslh, DescriptorSetLayout&& info, utils::CString&& tag) {
+        Handle<HwDescriptorSetLayout> dslh, DescriptorSetLayout&& info, utils::CString tag) {
 #if FILAMENT_METAL_DEBUG_LOG == 1
    const char* labelStr = "";
    std::visit([&labelStr](auto&& arg) {
@@ -758,11 +743,10 @@ void MetalDriver::createDescriptorSetLayoutR(
 }

 void MetalDriver::createDescriptorSetR(
-        Handle<HwDescriptorSet> dsh, Handle<HwDescriptorSetLayout> dslh, utils::CString&& tag) {
+        Handle<HwDescriptorSet> dsh, Handle<HwDescriptorSetLayout> dslh, utils::CString tag) {
    DEBUG_LOG("createDescriptorSetR(dsh = %d, dslh = %d)\n", dsh.getId(), dslh.getId());
    MetalDescriptorSetLayout* layout = handle_cast<MetalDescriptorSetLayout>(dslh);
-    MetalDescriptorSet* ds = construct_handle<MetalDescriptorSet>(dsh, layout);
-    ds->setLabel(tag);
+    construct_handle<MetalDescriptorSet>(dsh, layout);
    mHandleAllocator.associateTagToHandle(dsh.getId(), std::move(tag));
 }

@@ -1002,12 +986,8 @@ ShaderModel MetalDriver::getShaderModel() const noexcept {
 #endif
 }

-utils::FixedCapacityVector<ShaderLanguage> MetalDriver::getShaderLanguages(
-        ShaderLanguage preferredLanguage) const noexcept {
-    if (preferredLanguage == backend::ShaderLanguage::MSL) {
-        return { backend::ShaderLanguage::MSL, backend::ShaderLanguage::METAL_LIBRARY };
-    }
-    return { backend::ShaderLanguage::METAL_LIBRARY, backend::ShaderLanguage::MSL };
+ShaderLanguage MetalDriver::getShaderLanguage() const noexcept {
+    return ShaderLanguage::MSL;
 }

 Handle<HwStream> MetalDriver::createStreamNative(void* stream, utils::CString tag) {
@@ -1042,15 +1022,11 @@ void MetalDriver::destroyFence(Handle<HwFence> fh) {
 }

 FenceStatus MetalDriver::getFenceStatus(Handle<HwFence> fh) {
-    return fenceWait(fh, 0);
-}
-
-FenceStatus MetalDriver::fenceWait(FenceHandle fh, uint64_t const timeout) {
    auto* fence = handle_cast<MetalFence>(fh);
    if (!fence) {
        return FenceStatus::ERROR;
    }
-    return fence->wait(timeout);
+    return fence->wait(0);
 }

 void MetalDriver::destroySync(Handle<HwSync> sh) {
@@ -2225,38 +2201,6 @@ void MetalDriver::executeDeferredOps() noexcept {
    }
 }

-MemoryMappedBufferHandle MetalDriver::mapBufferS() noexcept {
-    return alloc_handle<MetalMemoryMappedBuffer>();
-}
-
-void MetalDriver::mapBufferR(MemoryMappedBufferHandle mmbh,
-        BufferObjectHandle boh, size_t offset,
-        size_t size, MapBufferAccessFlags access, utils::CString&& tag) {
-    construct_handle<MetalMemoryMappedBuffer>(mmbh, boh, offset, size, access);
-    mHandleAllocator.associateTagToHandle(mmbh.getId(), std::move(tag));
-}
-
-void MetalDriver::unmapBuffer(MemoryMappedBufferHandle mmbh) {
-    if (UTILS_UNLIKELY(!mmbh)) {
-        return;
-    }
-    destruct_handle<MetalMemoryMappedBuffer>(mmbh);
-}
-
-void MetalDriver::copyToMemoryMappedBuffer(MemoryMappedBufferHandle mmbh, size_t offset,
-        BufferDescriptor&& data) {
-    auto mmb = handle_cast<MetalMemoryMappedBuffer>(mmbh);
-
-    assert_invariant(any(mmb->access & MapBufferAccessFlags::WRITE_BIT));
-    assert_invariant(offset + data.size <= mmb->size);
-
-    // TODO: this isa zero-effort implementation of copyToMemoryMappedBuffer(), where we just
-    //       call updateBufferObject(). This could be a fallback implementation for when
-    //       shared memory is not available.
-    //       On UMA systems, this should just be a memcpy into the memory-mapped buffer.
-    updateBufferObject(mmb->boh, std::move(data), mmb->offset + offset);
-}
-
 // explicit instantiation of the Dispatcher
 template class ConcreteDispatcher<MetalDriver>;

@@ -451,38 +451,6 @@ inline MTLTextureSwizzleChannels getSwizzleChannels(TextureSwizzle r, TextureSwi
            getSwizzle(a));
 }

-inline const char* stringifyMTLCommandBufferError(MTLCommandBufferError error) {
-#if !defined(FILAMENT_IOS)
-    if (error == MTLCommandBufferErrorDeviceRemoved) {
-        return "MTLCommandBufferErrorDeviceRemoved";
-    }
-#endif
-    switch (error) {
-        case MTLCommandBufferErrorNone:
-            return "MTLCommandBufferErrorNone";
-        case MTLCommandBufferErrorInternal:
-            return "MTLCommandBufferErrorInternal";
-        case MTLCommandBufferErrorTimeout:
-            return "MTLCommandBufferErrorTimeout";
-        case MTLCommandBufferErrorPageFault:
-            return "MTLCommandBufferErrorPageFault";
-        case MTLCommandBufferErrorAccessRevoked:
-            return "MTLCommandBufferErrorAccessRevoked";
-        case MTLCommandBufferErrorNotPermitted:
-            return "MTLCommandBufferErrorNotPermitted";
-        case MTLCommandBufferErrorOutOfMemory:
-            return "MTLCommandBufferErrorOutOfMemory";
-        case MTLCommandBufferErrorInvalidResource:
-            return "MTLCommandBufferErrorInvalidResource";
-        case MTLCommandBufferErrorMemoryless:
-            return "MTLCommandBufferErrorMemoryless";
-        case MTLCommandBufferErrorStackOverflow:
-            return "MTLCommandBufferErrorStackOverflow";
-        default:
-            return "Unknown";
-    }
-}
-
 } // namespace backend
 } // namespace filament

@@ -1,28 +0,0 @@
-/*
- * Copyright (C) 2025 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_DRIVER_METALFLAGS_H
-#define TNT_FILAMENT_DRIVER_METALFLAGS_H
-
-#ifndef FILAMENT_METAL_DEBUG_LABELS
-#ifndef NDEBUG
-#define FILAMENT_METAL_DEBUG_LABELS 1
-#else
-#define FILAMENT_METAL_DEBUG_LABELS 0
-#endif
-#endif
-
-#endif
@@ -27,7 +27,6 @@
 #include "MetalContext.h"
 #include "MetalEnums.h"
 #include "MetalExternalImage.h"
-#include "MetalFlags.h"
 #include "MetalState.h" // for MetalState::VertexDescription

 #include <backend/DriverEnums.h>
@@ -267,16 +266,6 @@ public:

    static MTLPixelFormat decidePixelFormat(MetalContext* context, TextureFormat format);

-    void setLabel(const utils::CString& label) {
-#if FILAMENT_METAL_DEBUG_LABELS
-        if (label.empty()) {
-            return;
-        }
-        texture.label = @(label.c_str_safe());
-        swizzledTextureView.label = @(label.c_str_safe());
-#endif
-    }
-
    MetalContext& context;

    // A "sidecar" texture used to implement automatic MSAA resolve.
@@ -494,15 +483,6 @@ struct MetalDescriptorSet : public HwDescriptorSet {

    void finalize(MetalDriver* driver);

-    void setLabel(const utils::CString& l) {
-#if FILAMENT_METAL_DEBUG_LABELS
-        if (l.empty()) {
-            return;
-        }
-        label = l;
-#endif
-    }
-
    id<MTLBuffer> finalizeAndGetBuffer(MetalDriver* driver, ShaderStage stage);

    MetalDescriptorSetLayout* layout;
@@ -525,22 +505,6 @@ struct MetalDescriptorSet : public HwDescriptorSet {
    std::vector<std::shared_ptr<MetalExternalImage>> externalImages;

    std::array<TrackedMetalBuffer, Program::SHADER_TYPE_COUNT> cachedBuffer = { nil };
-
-#if FILAMENT_METAL_DEBUG_LABELS
-    utils::CString label;
-#endif
-};
-
-
-struct MetalMemoryMappedBuffer : public HwMemoryMappedBuffer {
-    MetalMemoryMappedBuffer(BufferObjectHandle boh, size_t const offset,
-            size_t const size, MapBufferAccessFlags const access)
-        : boh(boh), access(access), size(size), offset(offset) {
-    }
-    BufferObjectHandle boh{};
-    MapBufferAccessFlags access{};
-    uint32_t size = 0;
-    uint32_t offset = 0;
 };

 } // namespace backend
@@ -295,12 +295,6 @@ void MetalSwapChain::ensureDepthStencilTexture() {

 void MetalSwapChain::setFrameScheduledCallback(
        CallbackHandler* handler, FrameScheduledCallback&& callback, uint64_t flags) {
-    if (!callback) {
-        frameScheduled.handler = nullptr;
-        frameScheduled.callback.reset();
-        frameScheduled.flags = 0;
-        return;
-    }
    frameScheduled.handler = handler;
    frameScheduled.callback = std::make_shared<FrameScheduledCallback>(std::move(callback));
    frameScheduled.flags = flags;
@@ -1492,11 +1486,6 @@ id<MTLBuffer> MetalDescriptorSet::finalizeAndGetBuffer(MetalDriver* driver, Shad
        buffer = { [context.device newBufferWithLength:encoder.encodedLength
                                               options:MTLResourceStorageModeShared],
            TrackedMetalBuffer::Type::DESCRIPTOR_SET };
-#if FILAMENT_METAL_DEBUG_LABELS
-        if (!label.empty()) {
-            buffer.get().label = @(label.c_str_safe());
-        }
-#endif
    }
    [encoder setArgumentBuffer:buffer.get() offset:0];

@@ -134,7 +134,6 @@ bool MetalShaderCompiler::isParallelShaderCompileSupported() const noexcept {
            case ShaderLanguage::ESSL3:
            case ShaderLanguage::SPIRV:
            case ShaderLanguage::WGSL:
-            case ShaderLanguage::UNSPECIFIED:
                break;
        }

@@ -155,11 +155,9 @@ id<MTLSamplerState> SamplerStateCreator::operator()(id<MTLDevice> device,
    // Older Apple devices (and the simulator) don't support setting a comparison function in
    // MTLSamplerDescriptor.
    // In practice, this means shadows are not supported when running in the simulator.
-    if (samplerDescriptor.compareFunction != MTLCompareFunctionNever) {
-        if (![device supportsFeatureSet:MTLFeatureSet_iOS_GPUFamily3_v1]) {
-            LOG(WARNING) << "Warning: sample comparison not supported by this GPU";
-            samplerDescriptor.compareFunction = MTLCompareFunctionNever;
-        }
+    if (![device supportsFeatureSet:MTLFeatureSet_iOS_GPUFamily3_v1]) {
+        LOG(WARNING) << "Warning: sample comparison not supported by this GPU";
+        samplerDescriptor.compareFunction = MTLCompareFunctionNever;
    }
 #endif

@@ -45,16 +45,8 @@ ShaderModel NoopDriver::getShaderModel() const noexcept {
 #endif
 }

-utils::FixedCapacityVector<ShaderLanguage> NoopDriver::getShaderLanguages(
-        ShaderLanguage /*preferredLanguage*/) const noexcept {
-    return {
-        ShaderLanguage::ESSL3,
-        ShaderLanguage::ESSL1,
-        ShaderLanguage::SPIRV,
-        ShaderLanguage::MSL,
-        ShaderLanguage::METAL_LIBRARY,
-        ShaderLanguage::WGSL,
-    };
+ShaderLanguage NoopDriver::getShaderLanguage() const noexcept {
+    return ShaderLanguage::ESSL3;
 }

 // explicit instantiation of the Dispatcher
@@ -168,10 +160,6 @@ FenceStatus NoopDriver::getFenceStatus(Handle<HwFence> fh) {
    return FenceStatus::CONDITION_SATISFIED;
 }

-FenceStatus NoopDriver::fenceWait(Handle<HwFence> fh, uint64_t timeout) {
-    return FenceStatus::ERROR;
-}
-
 // We create all textures using VK_IMAGE_TILING_OPTIMAL, so our definition of "supported" is that
 // the GPU supports the given texture format with non-zero optimal tiling features.
 bool NoopDriver::isTextureFormatSupported(TextureFormat format) {
@@ -340,8 +328,8 @@ void NoopDriver::makeCurrent(Handle<HwSwapChain> drawSch, Handle<HwSwapChain> re
 void NoopDriver::commit(Handle<HwSwapChain> sch) {
 }

-void NoopDriver::setPushConstant(ShaderStage stage, uint8_t index,
-        PushConstantVariant value) {
+void NoopDriver::setPushConstant(backend::ShaderStage stage, uint8_t index,
+        backend::PushConstantVariant value) {
 }

 void NoopDriver::insertEventMarker(char const* string) {
@@ -365,8 +353,8 @@ void NoopDriver::readPixels(Handle<HwRenderTarget> src,
    scheduleDestroy(std::move(p));
 }

-void NoopDriver::readBufferSubData(BufferObjectHandle boh,
-        uint32_t offset, uint32_t size, BufferDescriptor&& p) {
+void NoopDriver::readBufferSubData(backend::BufferObjectHandle boh,
+        uint32_t offset, uint32_t size, backend::BufferDescriptor&& p) {
    scheduleDestroy(std::move(p));
 }

@@ -417,31 +405,24 @@ void NoopDriver::resetState(int) {
 }

 void NoopDriver::updateDescriptorSetBuffer(
-        DescriptorSetHandle dsh,
-        descriptor_binding_t binding,
-        BufferObjectHandle boh,
+        backend::DescriptorSetHandle dsh,
+        backend::descriptor_binding_t binding,
+        backend::BufferObjectHandle boh,
        uint32_t offset,
        uint32_t size) {
 }

 void NoopDriver::updateDescriptorSetTexture(
-        DescriptorSetHandle dsh,
-        descriptor_binding_t binding,
-        TextureHandle th,
+        backend::DescriptorSetHandle dsh,
+        backend::descriptor_binding_t binding,
+        backend::TextureHandle th,
        SamplerParams params) {
 }

 void NoopDriver::bindDescriptorSet(
-        DescriptorSetHandle dsh,
-        descriptor_set_t set,
-        DescriptorSetOffsetArray&& offsets) {
-}
-
-void NoopDriver::unmapBuffer(MemoryMappedBufferHandle mmbh) {
-}
-
-void NoopDriver::copyToMemoryMappedBuffer(MemoryMappedBufferHandle mmbh, size_t offset,
-        BufferDescriptor&& data) {
+        backend::DescriptorSetHandle dsh,
+        backend::descriptor_set_t set,
+        backend::DescriptorSetOffsetArray&& offsets) {
 }

 } // namespace filament
@@ -20,7 +20,6 @@
 #include "private/backend/Driver.h"
 #include "DriverBase.h"

-#include <utils/FixedCapacityVector.h>
 #include <utils/compiler.h>

 namespace filament::backend {
@@ -35,8 +34,7 @@ public:

 private:
    ShaderModel getShaderModel() const noexcept final;
-    utils::FixedCapacityVector<ShaderLanguage> getShaderLanguages(
-            ShaderLanguage preferredLanguage) const noexcept final;
+    ShaderLanguage getShaderLanguage() const noexcept final;

    uint64_t nextFakeHandle = 1;

@@ -40,12 +40,10 @@ struct GLBufferObject : public HwBufferObject {
            GLenum binding;
            void* buffer;
        };
-    } gl{};
-    BufferUsage usage                   : 4;
-    BufferObjectBinding bindingType     : 4;
-    uint8_t mappingCount = 0;
+    } gl;
+    BufferUsage usage;
+    BufferObjectBinding bindingType;
    uint16_t age = 0;
-
 };

 } // namespace filament::backend
@@ -1,154 +0,0 @@
-/*
- * Copyright (C) 2025 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "GLMemoryMappedBuffer.h"
-
-#include "GLBufferObject.h"
-#include "GLUtils.h"
-#include "OpenGLContext.h"
-#include "OpenGLDriver.h"
-
-#include "gl_headers.h"
-
-#include <private/backend/HandleAllocator.h>
-
-#include <backend/DriverEnums.h>
-#include <backend/Handle.h>
-
-#include <utils/compiler.h>
-#include <utils/debug.h>
-#include <utils/BitmaskEnum.h>
-
-#include <limits>
-#include <utility>
-
-#include <stddef.h>
-#include <stdint.h>
-#include <string.h>
-
-namespace filament::backend {
-
-GLMemoryMappedBuffer::GLMemoryMappedBuffer() = default;
-
-GLMemoryMappedBuffer::~GLMemoryMappedBuffer() = default;
-
-GLMemoryMappedBuffer::GLMemoryMappedBuffer(OpenGLContext& glc, HandleAllocatorGL& handleAllocator,
-        BufferObjectHandle boh,
-        size_t const offset, size_t const size, MapBufferAccessFlags const access)
-            : boh(boh), access(access) {
-
-    GLBufferObject* const bo = handleAllocator.handle_cast<GLBufferObject*>(boh);
-
-    assert_invariant(bo);
-    assert_invariant(bo->mappingCount < std::numeric_limits<uint8_t>::max());
-    assert_invariant(offset + size <= bo->byteCount);
-
-    if (any(access & MapBufferAccessFlags::WRITE_BIT)) {
-        assert_invariant(any(bo->usage & BufferUsage::SHARED_WRITE_BIT));
-    }
-
-    if (UTILS_UNLIKELY(glc.isES2())) {
-        gl.vaddr = static_cast<char*>(bo->gl.buffer) + offset;
-        gl.size = size;
-        gl.offset = offset;
-        gl.binding = 0; // in ES2 mode, bo->gl.binding is not available
-        gl.id = bo->gl.id;
-        bo->age++; // technically we could do this only in copy()
-        bo->mappingCount++;
-        return;
-    }
-
-#if !defined(FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2)
-        void* addr = nullptr;
-
-#   if !defined(__EMSCRIPTEN__)
-        // unsynchronized is implied (but is incompatible with reading)
-        GLbitfield gl_access = GL_MAP_UNSYNCHRONIZED_BIT;
-        if (any(access & MapBufferAccessFlags::WRITE_BIT)) {
-            gl_access |= GL_MAP_WRITE_BIT;
-        }
-        if (any(access & MapBufferAccessFlags::INVALIDATE_RANGE_BIT)) {
-            // note: GL_MAP_INVALIDATE_RANGE_BIT is incompatible with GL_MAP_READ_BIT
-            gl_access |= GL_MAP_INVALIDATE_RANGE_BIT;
-        }
-
-        glc.bindBuffer(bo->gl.binding, bo->gl.id);
-
-        addr = glMapBufferRange(bo->gl.binding, GLsizeiptr(offset), GLsizeiptr(size), gl_access);
-
-        CHECK_GL_ERROR();
-#   endif
-
-    // if we failed here, addr would be nullptr
-    gl.vaddr = addr;
-    gl.size = size;
-    gl.offset = offset;
-    gl.binding = bo->gl.binding;
-    gl.id = bo->gl.id;
-    bo->mappingCount++;
-
-#endif
-}
-
-void GLMemoryMappedBuffer::unmap(OpenGLContext& glc, HandleAllocatorGL& handleAllocator) const {
-    GLBufferObject* const bo = handleAllocator.handle_cast<GLBufferObject*>(boh);
-    assert_invariant(bo);
-    assert_invariant(bo->mappingCount > 0);
-
-    bo->mappingCount--;
-
-    if (UTILS_UNLIKELY(glc.isES2())) {
-        // nothing to do
-        return;
-    }
-
-#ifndef FILAMENT_SILENCE_NOT_SUPPORTED_BY_ES2
-    glc.bindBuffer(gl.binding, gl.id);
-#   if !defined(__EMSCRIPTEN__)
-        // don't unmap if we don't have a mapping or it didn't work
-        if (UTILS_LIKELY(gl.vaddr)) {
-            if (UTILS_UNLIKELY(glUnmapBuffer(gl.binding) == GL_FALSE)) {
-                // TODO: According to the spec, UnmapBuffer can return FALSE in rare conditions (e.g.
-                //   during a screen mode change). Note that this is not a GL error, but the whole
-                //   mapping is lost. This is very problematic for us here.
-            }
-            CHECK_GL_ERROR();
-        }
-#   endif
-#endif
-}
-
-void GLMemoryMappedBuffer::copy(OpenGLContext& glc, OpenGLDriver& gld,
-        size_t const offset, BufferDescriptor&& data) const {
-    assert_invariant(any(access & MapBufferAccessFlags::WRITE_BIT));
-    assert_invariant(offset + data.size <= gl.size);
-
-    if (UTILS_LIKELY(gl.vaddr)) {
-        memcpy(static_cast<char *>(gl.vaddr) + offset, data.buffer, data.size);
-    } else {
-        assert_invariant(!glc.isES2());
-        // we couldn't map (WebGL or error), revert to glBufferSubData. In the future we can
-        // improve this by keeping around the BufferDescriptor and coalescing the calls
-        // to glBufferSubData.
-        glc.bindBuffer(gl.binding, gl.id);
-        glBufferSubData(gl.binding, GLintptr(gl.offset + offset), GLsizeiptr(data.size), data.buffer);
-        CHECK_GL_ERROR();
-    }
-
-    gld.scheduleDestroy(std::move(data));
-}
-
-} // namespace filament::backend
@@ -1,66 +0,0 @@
-/*
- * Copyright (C) 2025 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_OPENGL_GLMEMORYMAPPEDBUFFER_H
-#define TNT_FILAMENT_BACKEND_OPENGL_GLMEMORYMAPPEDBUFFER_H
-
-#include "DriverBase.h"
-
-#include <private/backend/HandleAllocator.h>
-
-#include <backend/DriverEnums.h>
-#include <backend/Handle.h>
-
-#include "gl_headers.h"
-
-#include <stddef.h>
-#include <stdint.h>
-
-namespace filament::backend {
-
-class OpenGLContext;
-class OpenGLDriver;
-class BufferDescriptor;
-
-struct GLBufferObject;
-
-struct GLMemoryMappedBuffer : public HwMemoryMappedBuffer {
-    BufferObjectHandle boh;
-    MapBufferAccessFlags access;
-    struct {
-        void* vaddr = nullptr;
-        uint32_t size = 0;
-        uint32_t offset = 0;
-        GLenum binding = 0;
-        GLuint id = 0;
-    } gl;
-
-    GLMemoryMappedBuffer();
-
-    GLMemoryMappedBuffer(OpenGLContext& glc, HandleAllocatorGL& handleAllocator,
-            BufferObjectHandle boh, size_t offset, size_t size, MapBufferAccessFlags access);
-
-    ~GLMemoryMappedBuffer();
-
-    void unmap(OpenGLContext& gl, HandleAllocatorGL& handleAllocator) const;
-
-    void copy(OpenGLContext& glc, OpenGLDriver& gld,
-            size_t offset, BufferDescriptor&& data) const;
-};
-
-} // namespace filament::backend
-
-#endif //TNT_FILAMENT_BACKEND_OPENGL_GLMEMORYMAPPEDBUFFER_H
@@ -21,14 +21,12 @@

 #include <backend/platforms/OpenGLPlatform.h>
 #include <backend/DriverEnums.h>
-#include <backend/Platform.h>

 #include <utils/Logger.h>
 #include <utils/compiler.h>
 #include <utils/debug.h>
 #include <utils/ostream.h>

-#include <algorithm>
 #include <functional>
 #include <string_view>
 #include <utility>
@@ -103,8 +101,6 @@ OpenGLContext::OpenGLContext(OpenGLPlatform& platform,
    initBugs(&bugs, ext, state.major, state.minor,
            state.vendor, state.renderer, state.version, state.shader);

-    initWorkarounds(bugs, &ext);
-
    glGetIntegerv(GL_MAX_RENDERBUFFER_SIZE,             &gets.max_renderbuffer_size);
    glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS,           &gets.max_texture_image_units);
    glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS,  &gets.max_combined_texture_image_units);
@@ -507,40 +503,20 @@ void OpenGLContext::initBugs(Bugs* bugs, Extensions const& exts,
        } else if (strstr(renderer, "Mali")) {
            // ARM GPU
            bugs->vao_doesnt_store_element_array_buffer_binding = true;
-
-            // We have run into several problems with timer queries on Mali-Gxx:
-            // - timer queries seem to cause memory corruptions in some cases on some devices
-            //   (see b/233754398)
-            //          - appeared at least in: "OpenGL ES 3.2 v1.r26p0-01eac0"
-            //          - wasn't present in: "OpenGL ES 3.2 v1.r32p1-00pxl1"
-            // - timer queries sometime crash with an NPE (see b/273759031)
-            //   (see b/273759031)
-            //          - possibly not present in: "OpenGL ES 3.2 v1.r46p0"
-            bugs->dont_use_timer_query = true;
-
-            // at least some version of Mali have problems with framebuffer_fetch
-            // (see b/445721121, https://github.com/google/filament/issues/7794)
-            bugs->disable_framebuffer_fetch_extension = true;
-
            if (strstr(renderer, "Mali-T")) {
                bugs->disable_glFlush = true;
                bugs->disable_shared_context_draws = true;
+                // We have not verified that timer queries work on Mali-T, so we disable to be safe.
+                bugs->dont_use_timer_query = true;
            }
            if (strstr(renderer, "Mali-G")) {
-                int maj, min, driverVersion, driverRelease;
-                int const c = sscanf(version, "OpenGL ES %d.%d v%d.r%d",
-                        &maj, &min, &driverVersion, &driverRelease);
-                if (UTILS_LIKELY(c == 4)) {
-                    // we were able to parse the version string
-                    if (driverVersion > 1 || (driverVersion == 1 && driverRelease >= 46)) {
-                        // this driver version is known to be good
-                        bugs->dont_use_timer_query = false;
-                    }
-                    if (driverVersion > 1 || (driverVersion == 1 && driverRelease >= 53)) {
-                        // this driver version is known to be good
-                        bugs->disable_framebuffer_fetch_extension = false;
-                    }
-                }
+                // We have run into several problems with timer queries on Mali-Gxx:
+                // - timer queries seem to cause memory corruptions in some cases on some devices
+                //   (see b/233754398)
+                //          - appeared at least in: "OpenGL ES 3.2 v1.r26p0-01eac0"
+                //          - wasn't present in: "OpenGL ES 3.2 v1.r32p1-00pxl1"
+                // - timer queries sometime crash with an NPE (see b/273759031)
+                bugs->dont_use_timer_query = true;
            }
            // Mali seems to have no problem with this (which is good for us)
            bugs->allow_read_only_ancillary_feedback_loop = true;
@@ -583,22 +559,13 @@ void OpenGLContext::initBugs(Bugs* bugs, Extensions const& exts,
        }

        if (strstr(vendor, "Mesa")) {
-            if (strstr(renderer, "llvmpipe")) {
-                // Seen on
-                //  [Mesa],
-                //  [llvmpipe (LLVM 17.0.6, 256 bits)],
-                //  [4.5 (Core Profile) Mesa 24.0.6-1],
-                //  [4.50]
-                // not known which version are affected
-                bugs->rebind_buffer_after_deletion = true;
-
-                // Seen on
-                // [Mesa]
-                // [llvmpipe (LLVM 17.0.6, 256 bits)]
-                // [4.5 (Core Profile) Mesa 24.2.1 (git-c222f7299c)]
-                // [4.50]
-                bugs->disable_framebuffer_fetch_extension = true;
-            }
+            // Seen on
+            //  [Mesa],
+            //  [llvmpipe (LLVM 17.0.6, 256 bits)],
+            //  [4.5 (Core Profile) Mesa 24.0.6-1],
+            //  [4.50]
+            // not known which version are affected
+            bugs->rebind_buffer_after_deletion = true;
        }
    } else {
        // When running under ANGLE, it's a different set of workaround that we need.
@@ -644,12 +611,6 @@ void OpenGLContext::initBugs(Bugs* bugs, Extensions const& exts,
 #endif
 }

-void OpenGLContext::initWorkarounds(Bugs const& bugs, Extensions* ext) {
-    if (bugs.disable_framebuffer_fetch_extension) {
-        ext->EXT_shader_framebuffer_fetch = false;
-    }
-}
-
 FeatureLevel OpenGLContext::resolveFeatureLevel(GLint major, GLint minor,
        Extensions const& exts,
        Gets const& gets,
@@ -334,13 +334,6 @@ public:
        // those particular browsers.
        bool disable_depth_precache_for_default_material;

-        // On llvmpipe (mesa), enabling framebuffer fetch causes a crash in draw2
-        //   'OpenGL error 0x502 (GL_INVALID_OPERATION) in "draw2" at line 4389'
-        // This coincides with the use of framebuffer fetch (ColorGradingAsSubpass). We disable
-        // framebuffer fetch in the case of llvmpipe.
-        // Some Mali drivers also have problems with this (b/445721121)
-        bool disable_framebuffer_fetch_extension;
-
    } bugs = {};

    // state getters -- as needed.
@@ -584,9 +577,6 @@ private:
            {   bugs.disable_depth_precache_for_default_material,
                    "disable_depth_precache_for_default_material",
                    ""},
-            {   bugs.disable_framebuffer_fetch_extension,
-                    "disable_framebuffer_fetch_extension",
-                    ""},
    }};

    // this is chosen to minimize code size
@@ -617,8 +607,6 @@ private:
    static void initProcs(Procs* procs,
            Extensions const& exts, GLint major, GLint minor) noexcept;

-    static void initWorkarounds(Bugs const& bugs, Extensions* ext);
-
    static FeatureLevel resolveFeatureLevel(GLint major, GLint minor,
            Extensions const& exts,
            Gets const& gets,
@@ -24,7 +24,6 @@
 #include "GLBufferObject.h"
 #include "GLDescriptorSet.h"
 #include "GLDescriptorSetLayout.h"
-#include "GLMemoryMappedBuffer.h"
 #include "GLTexture.h"
 #include "ShaderCompilerService.h"

@@ -103,7 +102,7 @@ public:
        bool rec709 = false;
        struct {
            CallbackHandler* handler = nullptr;
-            std::shared_ptr<FrameScheduledCallback> callback = nullptr;
+            FrameScheduledCallback callback;
        } frameScheduled;
    };

@@ -152,8 +151,6 @@ public:

    using GLDescriptorSet = filament::backend::GLDescriptorSet;

-    using GLMemoryMappedBuffer = filament::backend::GLMemoryMappedBuffer;
-
    struct GLStream : public HwStream {
        using HwStream::HwStream;
        struct Info {
@@ -194,8 +191,8 @@ public:
    struct GLFence : public HwFence {
        using HwFence::HwFence;
        struct State {
-            utils::Mutex lock; // NOLINT(*-include-cleaner)
-            utils::Condition cond; // NOLINT(*-include-cleaner)
+            std::mutex lock;
+            std::condition_variable cond;
            FenceStatus status{ FenceStatus::TIMEOUT_EXPIRED };
        };
        std::shared_ptr<State> state{ std::make_shared<State>() };
@@ -217,8 +214,6 @@ public:
    OpenGLDriver(OpenGLDriver const&) = delete;
    OpenGLDriver& operator=(OpenGLDriver const&) = delete;

-    using DriverBase::scheduleDestroy;
-
 private:
    OpenGLPlatform& mPlatform;
    OpenGLContext mContext;
@@ -233,8 +228,7 @@ private:
    }

    ShaderModel getShaderModel() const noexcept override;
-    utils::FixedCapacityVector<ShaderLanguage> getShaderLanguages(
-            ShaderLanguage preferredLanguage) const noexcept override;
+    ShaderLanguage getShaderLanguage() const noexcept override;

    /*
     * OpenGLDriver interface
@@ -322,7 +322,6 @@ Driver* PlatformEGL::createDriver(void* sharedContext, const DriverConfig& drive

    mCurrentContextType = ContextType::UNPROTECTED;
    mContextAttribs = std::move(contextAttribs);
-    mMSAA4XSupport = checkIfMSAASwapChainSupported(4);

    initializeGlExtensions();

@@ -492,11 +491,34 @@ bool PlatformEGL::isMSAASwapChainSupported(uint32_t samples) const noexcept {
        return true;
    }

-    if (samples == 4) {
-        return mMSAA4XSupport;
+    Config configAttribs = {
+            { EGL_SURFACE_TYPE,    EGL_WINDOW_BIT | EGL_PBUFFER_BIT },
+            { EGL_RED_SIZE,        8 },
+            { EGL_GREEN_SIZE,      8 },
+            { EGL_BLUE_SIZE,       8 },
+            { EGL_DEPTH_SIZE,      24 },
+            { EGL_SAMPLE_BUFFERS,  1 },
+            { EGL_SAMPLES,         samples },
+    };
+
+    if (!ext.egl.KHR_no_config_context) {
+        if (isOpenGL()) {
+            configAttribs[EGL_RENDERABLE_TYPE] = EGL_OPENGL_BIT;
+        } else {
+            configAttribs[EGL_RENDERABLE_TYPE] = EGL_OPENGL_ES2_BIT;
+            if (ext.egl.KHR_create_context) {
+                configAttribs[EGL_RENDERABLE_TYPE] |= EGL_OPENGL_ES3_BIT_KHR;
+            }
+        }
    }

-    return false;
+    EGLConfig config = EGL_NO_CONFIG_KHR;
+    EGLint configsCount;
+    if (!eglChooseConfig(mEGLDisplay, configAttribs.data(), &config, 1, &configsCount)) {
+        return false;
+    }
+
+    return configsCount > 0;
 }

 Platform::SwapChain* PlatformEGL::createSwapChain(
@@ -816,38 +838,6 @@ EGLContext PlatformEGL::getContextForType(ContextType type) const noexcept {
    }
 }

-bool PlatformEGL::checkIfMSAASwapChainSupported(uint32_t samples) const noexcept {
-    // Retrieve the config to see if the given number of samples is supported. The result is cached.
-    Config configAttribs = {
-            { EGL_SURFACE_TYPE,    EGL_WINDOW_BIT | EGL_PBUFFER_BIT },
-            { EGL_RED_SIZE,        8 },
-            { EGL_GREEN_SIZE,      8 },
-            { EGL_BLUE_SIZE,       8 },
-            { EGL_DEPTH_SIZE,      24 },
-            { EGL_SAMPLE_BUFFERS,  1 },
-            { EGL_SAMPLES,         (EGLint)samples },
-    };
-
-    if (!ext.egl.KHR_no_config_context) {
-        if (isOpenGL()) {
-            configAttribs[EGL_RENDERABLE_TYPE] = EGL_OPENGL_BIT;
-        } else {
-            configAttribs[EGL_RENDERABLE_TYPE] = EGL_OPENGL_ES2_BIT;
-            if (ext.egl.KHR_create_context) {
-                configAttribs[EGL_RENDERABLE_TYPE] |= EGL_OPENGL_ES3_BIT_KHR;
-            }
-        }
-    }
-
-    EGLConfig config = EGL_NO_CONFIG_KHR;
-    EGLint configsCount;
-    if (!eglChooseConfig(mEGLDisplay, configAttribs.data(), &config, 1, &configsCount)) {
-        return false;
-    }
-
-    return configsCount > 0;
-}
-
 // ---------------------------------------------------------------------------------------------

 PlatformEGL::Config::Config() = default;
@@ -95,7 +95,11 @@ io::ostream& operator<<(io::ostream& out, ElementType type) {
 }

 io::ostream& operator<<(io::ostream& out, BufferUsage usage) {
-    return out << io::hex << uint32_t(usage) << io::dec;
+    switch (usage) {
+        CASE(BufferUsage, STATIC)
+        CASE(BufferUsage, DYNAMIC)
+    }
+    return out;
 }

 io::ostream& operator<<(io::ostream& out, CullingMode mode) {
@@ -1,82 +0,0 @@
-/*
- * Copyright (C) 2025 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "VulkanAsyncHandles.h"
-
-#include <backend/DriverEnums.h>
-
-#include <utils/debug.h>
-
-#include <cstdint>
-#include <mutex>
-#include <shared_mutex>
-#include <chrono>
-
-using namespace bluevk;
-
-namespace filament::backend {
-
-FenceStatus VulkanCmdFence::wait(VkDevice device, uint64_t const timeout,
-    std::chrono::steady_clock::time_point const until) {
-
-    std::shared_lock l(mLock);
-
-    // If the vulkan fence has not been submitted yet, we need to wait for that before we
-    // can use vkWaitForFences()
-    if (mStatus == VK_INCOMPLETE) {
-        bool const success = mCond.wait_until(l, until, [this] {
-            // Internally we use the VK_INCOMPLETE status to mean "not yet submitted".
-            // When this fence gets submitted, its status changes to VK_NOT_READY.
-            return mStatus != VK_INCOMPLETE;
-        });
-        if (!success) {
-            // !success indicates a timeout
-            return FenceStatus::TIMEOUT_EXPIRED;
-        }
-    }
-
-    // The fence could have already signaled, avoid calling into vkWaitForFences()
-    if (mStatus == VK_SUCCESS) {
-        return FenceStatus::CONDITION_SATISFIED;
-    }
-
-    // If we're here, we know that vkQueueSubmit has been called (because it sets the status
-    // to VK_NOT_READY).
-    // Now really wait for the fence while holding the shared_lock, this allows several
-    // threads to call vkWaitForFences(), but will prevent vkResetFence from taking
-    // place simultaneously. vkResetFence is only called once it knows the fence has signaled,
-    // which guaranties that vkResetFence won't have to wait too long, just enough for
-    // all the vkWaitForFences() to return.
-    mStatus = vkWaitForFences(device, 1, &mFence, VK_TRUE, timeout);
-    if (mStatus == VK_SUCCESS) {
-        return FenceStatus::CONDITION_SATISFIED;
-    }
-    if (mStatus == VK_TIMEOUT) {
-        return FenceStatus::TIMEOUT_EXPIRED;
-    }
-    return FenceStatus::ERROR; // not supported
-}
-
-void VulkanCmdFence::resetFence(VkDevice device) {
-    // This lock prevents vkResetFences() from being called simultaneously with vkWaitForFences(),
-    // but by construction, when we're here, we know that the fence has signaled and
-    // vkWaitForFences() will return shortly.
-    std::lock_guard const l(mLock);
-    assert_invariant(mStatus == VK_SUCCESS);
-    vkResetFences(device, 1, &mFence);
-}
-
-} // namespace filament::backend
@@ -20,81 +20,37 @@
 #include <bluevk/BlueVK.h>

 #include "DriverBase.h"
-#include "backend/DriverEnums.h"
 #include "backend/Platform.h"

 #include "vulkan/memory/Resource.h"

-#include <chrono>
-#include <cstdint>
-#include <memory>
-#include <mutex>
-#include <shared_mutex>
-#include <utility>
-#include <vector>
+#include <utils/Mutex.h>
+#include <utils/Condition.h>

 namespace filament::backend {

 // Wrapper to enable use of shared_ptr for implementing shared ownership of low-level Vulkan fences.
 struct VulkanCmdFence {
-    explicit VulkanCmdFence(VkFence fence) : mFence(fence) { }
+    VulkanCmdFence(VkResult initialStatus) {
+        // Internally we use the VK_INCOMPLETE status to mean "not yet submitted". When this fence
+        // gets submitted, its status changes to VK_NOT_READY. Finally, when the GPU actually
+        // finishes executing the command buffer, the status changes to VK_SUCCESS.
+        status.store(initialStatus);
+    }
+
    ~VulkanCmdFence() = default;

-    void setStatus(VkResult const value) {
-        std::lock_guard const l(mLock);
-        mStatus = value;
-        mCond.notify_all();
-    }
+    void setStatus(VkResult value) { status.store(value); }

-    VkResult getStatus() {
-        std::shared_lock const l(mLock);
-        return mStatus;
-    }
-
-    void resetFence(VkDevice device);
-
-    FenceStatus wait(VkDevice device, uint64_t timeout,
-        std::chrono::steady_clock::time_point until);
+    VkResult getStatus() { return status.load(std::memory_order_acquire); }

 private:
-    std::shared_mutex mLock; // NOLINT(*-include-cleaner)
-    std::condition_variable_any mCond;
-    // Internally we use the VK_INCOMPLETE status to mean "not yet submitted". When this fence
-    // gets submitted, its status changes to VK_NOT_READY. Finally, when the GPU actually
-    // finishes executing the command buffer, the status changes to VK_SUCCESS.
-    VkResult mStatus{ VK_INCOMPLETE };
-    VkFence mFence;
+    std::atomic<VkResult> status;
 };

 struct VulkanFence : public HwFence, fvkmemory::ThreadSafeResource {
    VulkanFence() {}
-
-    void setFence(std::shared_ptr<VulkanCmdFence> fence) {
-        std::lock_guard lock(mState->lock);
-        mState->sharedFence = std::move(fence);
-        mState->cond.notify_all();
-    }
-
-    std::shared_ptr<VulkanCmdFence>& getSharedFence() {
-        std::lock_guard lock(mState->lock);
-        return mState->sharedFence;
-    }
-
-    std::shared_ptr<VulkanCmdFence> wait(std::chrono::steady_clock::time_point const until) {
-        // hold a reference so that our state doesn't disappear while we wait
-        std::shared_ptr state{ mState };
-        std::unique_lock lock(state->lock);
-        state->cond.wait_until(lock, until, [&state] { return bool(state->sharedFence); });
-        // here mSharedFence will be null if we timed out
-        return state->sharedFence;
-    }
-private:
-    struct State {
-        std::mutex lock;
-        std::condition_variable cond;
-        std::shared_ptr<VulkanCmdFence> sharedFence;
-    };
-    std::shared_ptr<State> mState{ std::make_shared<State>() };
+    std::shared_ptr<VulkanCmdFence> fence;
 };

 struct VulkanSync : fvkmemory::ThreadSafeResource, public HwSync {
@@ -116,12 +72,12 @@ struct VulkanTimerQuery : public HwTimerQuery, fvkmemory::ThreadSafeResource {
          mStoppingQueryIndex(stoppingIndex) {}

    void setFence(std::shared_ptr<VulkanCmdFence> fence) noexcept {
-        std::unique_lock const lock(mFenceMutex);
-        mFence = std::move(fence);
+        std::unique_lock<utils::Mutex> lock(mFenceMutex);
+        mFence = fence;
    }

    bool isCompleted() noexcept {
-        std::unique_lock const lock(mFenceMutex);
+        std::unique_lock<utils::Mutex> lock(mFenceMutex);
        // QueryValue is a synchronous call and might occur before beginTimerQuery has written
        // anything into the command buffer, which is an error according to the validation layer
        // that ships in the Android NDK.  Even when AVAILABILITY_BIT is set, validation seems to
@@ -28,24 +28,24 @@ namespace filament::backend {

 namespace {

-VkBufferUsageFlags getVkBufferUsage(VulkanBufferBinding usage) {
+VkBufferUsageFlags getVkBufferUsage(VulkanBufferUsage usage) {
    switch (usage) {
-        case VulkanBufferBinding::VERTEX:
+        case VulkanBufferUsage::VERTEX:
            return VK_BUFFER_USAGE_VERTEX_BUFFER_BIT;
-        case VulkanBufferBinding::INDEX:
+        case VulkanBufferUsage::INDEX:
            return VK_BUFFER_USAGE_INDEX_BUFFER_BIT;
-        case VulkanBufferBinding::UNIFORM:
+        case VulkanBufferUsage::UNIFORM:
            return VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT;
-        case VulkanBufferBinding::SHADER_STORAGE:
+        case VulkanBufferUsage::SHADER_STORAGE:
            return VK_BUFFER_USAGE_STORAGE_BUFFER_BIT;
-        case VulkanBufferBinding::UNKNOWN:
+        case VulkanBufferUsage::UNKNOWN:
            return 0;
    }

    return 0;
 }

-} // namespace
+}// namespace

 VulkanBufferCache::VulkanBufferCache(VulkanContext const& context,
        fvkmemory::ResourceManager& resourceManager, VmaAllocator allocator)
@@ -53,11 +53,11 @@ VulkanBufferCache::VulkanBufferCache(VulkanContext const& context,
      mResourceManager(resourceManager),
      mAllocator(allocator) {}

-fvkmemory::resource_ptr<VulkanBuffer> VulkanBufferCache::acquire(VulkanBufferBinding binding,
+fvkmemory::resource_ptr<VulkanBuffer> VulkanBufferCache::acquire(VulkanBufferUsage usage,
        uint32_t numBytes) noexcept {
-    assert_invariant(binding != VulkanBufferBinding::UNKNOWN);
+    assert_invariant(usage != VulkanBufferUsage::UNKNOWN);

-    BufferPool& bufferPool = getPool(binding);
+    BufferPool& bufferPool = getPool(usage);

    // First check if an allocation exists whose capacity is greater than or equal to the requested
    // size.
@@ -71,7 +71,7 @@ fvkmemory::resource_ptr<VulkanBuffer> VulkanBufferCache::acquire(VulkanBufferBin

    // We were not able to find a sufficiently large allocation, so create a new one that is
    // recycled after being yielded.
-    VulkanGpuBuffer const* gpuBuffer = allocate(binding, numBytes);
+    VulkanGpuBuffer const* gpuBuffer = allocate(usage, numBytes);
    return fvkmemory::resource_ptr<VulkanBuffer>::construct(&mResourceManager, gpuBuffer,
            [this](VulkanGpuBuffer const* gpuBuffer) { this->release(gpuBuffer); });
 }
@@ -93,10 +93,9 @@ void VulkanBufferCache::gc() noexcept {
            if (poolIter->second.lastAccessed < evictionTime) {
 #if FVK_ENABLED(FVK_DEBUG_VULKAN_BUFFER_CACHE)
                FVK_LOGD << "VulkanBufferCache - Destroyed vkBuffer "
-                         << poolIter->second.gpuBuffer->vkbuffer << " with binding "
-                         << static_cast<int>(poolIter->second.gpuBuffer->binding)
-                         << utils::io::endl;
-#endif // FVK_DEBUG_VULKAN_BUFFER_CACHE
+                         << poolIter->second.gpuBuffer->vkbuffer << " with usage "
+                         << static_cast<int>(poolIter->second.gpuBuffer->usage) << utils::io::endl;
+#endif// FVK_DEBUG_VULKAN_BUFFER_CACHE

                destroy(poolIter->second.gpuBuffer);
                poolIter = bufferPool.erase(poolIter);
@@ -121,33 +120,35 @@ void VulkanBufferCache::terminate() noexcept {
 void VulkanBufferCache::release(VulkanGpuBuffer const* gpuBuffer) noexcept {
    assert_invariant(gpuBuffer != nullptr);

-    BufferPool& bufferPool = getPool(gpuBuffer->binding);
+    BufferPool& bufferPool = getPool(gpuBuffer->usage);
    bufferPool.insert(std::make_pair(gpuBuffer->numBytes, UnusedGpuBuffer{
                                                              .lastAccessed = mCurrentFrame,
                                                              .gpuBuffer = gpuBuffer,
                                                          }));
 }

-VulkanGpuBuffer const* VulkanBufferCache::allocate(VulkanBufferBinding binding,
+VulkanGpuBuffer const* VulkanBufferCache::allocate(VulkanBufferUsage usage,
        uint32_t numBytes) noexcept {
    VkBufferCreateInfo const bufferInfo{
        .sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO,
        .size = numBytes,
        // `VK_BUFFER_USAGE_TRANSFER_DST_BIT` is needed to allow updating the buffer through
        // a staging using `vkCmdCopyBuffer`.
-        .usage = getVkBufferUsage(binding) | VK_BUFFER_USAGE_TRANSFER_DST_BIT,
+        .usage = getVkBufferUsage(usage) | VK_BUFFER_USAGE_TRANSFER_DST_BIT,
    };

    VmaAllocationCreateFlags vmaFlags = 0;
-    // In the case of UMA, the buffers will always be mappable
-    if (mContext.isUnifiedMemoryArchitecture()) {
-        vmaFlags |= VMA_ALLOCATION_CREATE_MAPPED_BIT |
-                    VMA_ALLOCATION_CREATE_HOST_ACCESS_SEQUENTIAL_WRITE_BIT;
+    if (usage == VulkanBufferUsage::UNIFORM) {
+        // In the case of UMA, the uniform buffers will always be mappable
+        if (mContext.isUnifiedMemoryArchitecture()) {
+            vmaFlags |= VMA_ALLOCATION_CREATE_MAPPED_BIT |
+                        VMA_ALLOCATION_CREATE_HOST_ACCESS_SEQUENTIAL_WRITE_BIT;
+        }
    }

    VulkanGpuBuffer* gpuBuffer = new VulkanGpuBuffer{
        .numBytes = numBytes,
-        .binding = binding,
+        .usage = usage,
    };
    VmaAllocationCreateInfo const allocInfo{
        .flags = vmaFlags,
@@ -160,14 +161,14 @@ VulkanGpuBuffer const* VulkanBufferCache::allocate(VulkanBufferBinding binding,
 #if FVK_ENABLED(FVK_DEBUG_VULKAN_BUFFER_CACHE)
    if (result != VK_SUCCESS) {
        FVK_LOGE << "VulkanBufferCache - failed to allocate a new vkBuffer of size " << numBytes
-                 << " and binding " << static_cast<int>(binding) << ", error: " << result
+                 << " and usage " << static_cast<int>(usage) << ", error: " << result
                 << utils::io::endl;
    } else {
        FVK_LOGD << "VulkanBufferCache - allocated a vkBuffer " << gpuBuffer->vkbuffer
-                 << " of size " << numBytes << " and binding = " << static_cast<int>(binding)
+                 << " of size " << numBytes << " and usage = " << static_cast<int>(usage)
                 << "  successfully" << utils::io::endl;
    }
-#endif // FVK_DEBUG_VULKAN_BUFFER_CACHE
+#endif// FVK_DEBUG_VULKAN_BUFFER_CACHE

    return gpuBuffer;
 }
@@ -178,24 +179,24 @@ void VulkanBufferCache::destroy(VulkanGpuBuffer const* gpuBuffer) noexcept {
    gpuBuffer = nullptr;
 }

-VulkanBufferCache::BufferPool& VulkanBufferCache::getPool(VulkanBufferBinding binding) noexcept {
+VulkanBufferCache::BufferPool& VulkanBufferCache::getPool(VulkanBufferUsage usage) noexcept {

    int poolIndex = -1;
-    switch (binding) {
-        case VulkanBufferBinding::VERTEX:
+    switch (usage) {
+        case VulkanBufferUsage::VERTEX:
            poolIndex = 0;
            break;
-        case VulkanBufferBinding::INDEX:
+        case VulkanBufferUsage::INDEX:
            poolIndex = 1;
            break;
-        case VulkanBufferBinding::UNIFORM:
+        case VulkanBufferUsage::UNIFORM:
            poolIndex = 2;
            break;
-        case VulkanBufferBinding::SHADER_STORAGE:
+        case VulkanBufferUsage::SHADER_STORAGE:
            poolIndex = 3;
            break;
-        case VulkanBufferBinding::UNKNOWN:
-            PANIC_LOG("There's no pool for buffers with unkown binding.");
+        case VulkanBufferUsage::UNKNOWN:
+            PANIC_LOG("There's no pool for buffers with unkown usage.");
            break;
    }

@@ -203,4 +204,4 @@ VulkanBufferCache::BufferPool& VulkanBufferCache::getPool(VulkanBufferBinding bi
    return mGpuBufferPools[poolIndex];
 }

-} // namespace filament::backend
+}// namespace filament::backend
@@ -38,7 +38,7 @@ public:

    // Allocates or reuse a new VkBuffer that is device local.
    // In the case of Unified memory architecture, uniform buffers are also host visible.
-    fvkmemory::resource_ptr<VulkanBuffer> acquire(VulkanBufferBinding binding,
+    fvkmemory::resource_ptr<VulkanBuffer> acquire(VulkanBufferUsage usage,
            uint32_t numBytes) noexcept;

    // Evicts old unused `VulkanGpuBuffer` and bumps the current frame number
@@ -60,12 +60,12 @@ private:
    void release(VulkanGpuBuffer const* gpuBuffer) noexcept;

    // Allocate a new VkBuffer from the VMA pool of the corresponding `numBytes` and `usage`.
-    VulkanGpuBuffer const* allocate(VulkanBufferBinding binding, uint32_t numBytes) noexcept;
+    VulkanGpuBuffer const* allocate(VulkanBufferUsage usage, uint32_t numBytes) noexcept;

    // Destroy the corresponding VkBuffer and return the VkDeviceMemory to the VMA pool.
    void destroy(VulkanGpuBuffer const* gpuBuffer) noexcept;

-    BufferPool& getPool(VulkanBufferBinding binding) noexcept;
+    BufferPool& getPool(VulkanBufferUsage usage) noexcept;

    VulkanContext const& mContext;
    fvkmemory::ResourceManager& mResourceManager;
@@ -19,25 +19,22 @@
 #include "VulkanBufferCache.h"
 #include "VulkanCommands.h"
 #include "VulkanContext.h"
-#include "VulkanHandles.h"
 #include "VulkanMemory.h"
-
-#include <backend/DriverEnums.h>
+#include "VulkanHandles.h"

 using namespace bluevk;

 namespace filament::backend {

 VulkanBufferProxy::VulkanBufferProxy(VulkanContext const& context, VmaAllocator allocator,
-        VulkanStagePool& stagePool, VulkanBufferCache& bufferCache, VulkanBufferBinding binding,
-        BufferUsage usage, uint32_t numBytes)
+        VulkanStagePool& stagePool, VulkanBufferCache& bufferCache, VulkanBufferUsage usage,
+        uint32_t numBytes)
    : mStagingBufferBypassEnabled(context.stagingBufferBypassEnabled()),
      mAllocator(allocator),
      mStagePool(stagePool),
      mBufferCache(bufferCache),
-      mBuffer(mBufferCache.acquire(binding, numBytes)),
-      mLastReadAge(0),
-      mUsage(usage) {}
+      mBuffer(mBufferCache.acquire(usage, numBytes)),
+      mLastReadAge(0) {}

 void VulkanBufferProxy::loadFromCpu(VulkanCommandBuffer& commands, const void* cpuData,
        uint32_t byteOffset, uint32_t numBytes) {
@@ -52,18 +49,12 @@ void VulkanBufferProxy::loadFromCpu(VulkanCommandBuffer& commands, const void* c
    commands.acquire(mBuffer);

    // Check if we can just memcpy directly to the GPU memory.
+    // This is only allowed for UNIFORMS that are AVAILABLE and the memory is HOST_VISIBLE
+    // (supports memcpy from host). This works regardless if it's a full or partial update of the
+    // buffer.
    bool const isMemcopyable = mBuffer->getGpuBuffer()->allocationInfo.pMappedData != nullptr;
-
-    // In the case of UNIFORMS, check that is available to see to know if a memcpy is possible.
-    // This works regardless if it's a full or partial update of the buffer.
-    bool const isUniformAndAvailable = getBinding() == VulkanBufferBinding::UNIFORM && isAvailable;
-
-    // In the case the content is marked as memory mapped or static, is guaranteed to be safe to do
-    // a memcpy if its available.
-    bool const isStaticOrShared =
-            any(mUsage & (BufferUsage::STATIC | BufferUsage::SHARED_WRITE_BIT));
-    bool const useMemcpy = (isUniformAndAvailable || isStaticOrShared) && isMemcopyable &&
-                           mStagingBufferBypassEnabled;
+    bool const isUniform = getUsage() == VulkanBufferUsage::UNIFORM;
+    bool const useMemcpy = isUniform && isMemcopyable && isAvailable && mStagingBufferBypassEnabled;
    if (useMemcpy) {
        char* dest = static_cast<char*>(mBuffer->getGpuBuffer()->allocationInfo.pMappedData) +
                     byteOffset;
@@ -90,13 +81,13 @@ void VulkanBufferProxy::loadFromCpu(VulkanCommandBuffer& commands, const void* c
    if (!isAvailable) {
        VkAccessFlags srcAccess = 0;
        VkPipelineStageFlags srcStage = 0;
-        if (getBinding() == VulkanBufferBinding::UNIFORM) {
+        if (getUsage() == VulkanBufferUsage::UNIFORM) {
            srcAccess = VK_ACCESS_SHADER_READ_BIT;
            srcStage = VK_PIPELINE_STAGE_VERTEX_SHADER_BIT | VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT;
-        } else if (getBinding() == VulkanBufferBinding::VERTEX) {
+        } else if (getUsage() == VulkanBufferUsage::VERTEX) {
            srcAccess = VK_ACCESS_VERTEX_ATTRIBUTE_READ_BIT;
            srcStage = VK_PIPELINE_STAGE_VERTEX_INPUT_BIT;
-        } else if (getBinding() == VulkanBufferBinding::INDEX) {
+        } else if (getUsage() == VulkanBufferUsage::INDEX) {
            srcAccess = VK_ACCESS_INDEX_READ_BIT;
            srcStage = VK_PIPELINE_STAGE_VERTEX_INPUT_BIT;
        }
@@ -129,16 +120,16 @@ void VulkanBufferProxy::loadFromCpu(VulkanCommandBuffer& commands, const void* c
    VkAccessFlags dstAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
    VkPipelineStageFlags dstStageMask = VK_PIPELINE_STAGE_TRANSFER_BIT;

-    if (getBinding() == VulkanBufferBinding::VERTEX) {
+    if (getUsage() == VulkanBufferUsage::VERTEX) {
        dstAccessMask |= VK_ACCESS_VERTEX_ATTRIBUTE_READ_BIT;
        dstStageMask |= VK_PIPELINE_STAGE_VERTEX_INPUT_BIT;
-    } else if (getBinding() == VulkanBufferBinding::INDEX) {
+    } else if (getUsage() == VulkanBufferUsage::INDEX) {
        dstAccessMask |= VK_ACCESS_INDEX_READ_BIT;
        dstStageMask |= VK_PIPELINE_STAGE_VERTEX_INPUT_BIT;
-    } else if (getBinding() == VulkanBufferBinding::UNIFORM) {
+    } else if (getUsage() == VulkanBufferUsage::UNIFORM) {
        dstAccessMask |= VK_ACCESS_SHADER_READ_BIT;
        dstStageMask |= VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT | VK_PIPELINE_STAGE_VERTEX_SHADER_BIT;
-    } else if (getBinding() == VulkanBufferBinding::SHADER_STORAGE) {
+    } else if (getUsage() == VulkanBufferUsage::SHADER_STORAGE) {
        // TODO: implement me
    }

@@ -161,8 +152,8 @@ VkBuffer VulkanBufferProxy::getVkBuffer() const noexcept {
    return mBuffer->getGpuBuffer()->vkbuffer;
 }

-VulkanBufferBinding VulkanBufferProxy::getBinding() const noexcept {
-    return mBuffer->getGpuBuffer()->binding;
+VulkanBufferUsage VulkanBufferProxy::getUsage() const noexcept {
+    return mBuffer->getGpuBuffer()->usage;
 }

 void VulkanBufferProxy::referencedBy(VulkanCommandBuffer& commands) {
@@ -23,8 +23,6 @@
 #include "VulkanMemory.h"
 #include "VulkanStagePool.h"

-#include <backend/DriverEnums.h>
-
 namespace filament::backend {

 struct VulkanDescriptorSet;
@@ -35,8 +33,8 @@ struct VulkanCommandBuffer;
 class VulkanBufferProxy {
 public:
    VulkanBufferProxy(VulkanContext const& context, VmaAllocator allocator,
-            VulkanStagePool& stagePool, VulkanBufferCache& bufferCache, VulkanBufferBinding binding,
-            BufferUsage usage, uint32_t numBytes);
+            VulkanStagePool& stagePool, VulkanBufferCache& bufferCache, VulkanBufferUsage usage,
+            uint32_t numBytes);

    void loadFromCpu(VulkanCommandBuffer& commands, const void* cpuData, uint32_t byteOffset,
            uint32_t numBytes);
@@ -46,7 +44,7 @@ public:
    void referencedBy(VulkanCommandBuffer& commands);

 private:
-    VulkanBufferBinding getBinding() const noexcept;
+    VulkanBufferUsage getUsage() const noexcept;

    bool const mStagingBufferBypassEnabled;
    VmaAllocator mAllocator;
@@ -56,7 +54,6 @@ private:
    fvkmemory::resource_ptr<VulkanBuffer> mBuffer;

    uint32_t mLastReadAge;
-    BufferUsage mUsage;
 };

 } // namespace filament::backend
@@ -90,33 +90,30 @@ bool VulkanGroupMarkers::empty() const noexcept {
 uint32_t VulkanCommandBuffer::sAgeCounter = 0;

 VulkanCommandBuffer::VulkanCommandBuffer(VulkanContext const& context, VkDevice device,
-        VkQueue queue, VkCommandPool pool, VulkanSemaphoreManager* semaphoreManager,
-        bool isProtected)
+        VkQueue queue, VkCommandPool pool, bool isProtected)
    : mContext(context),
      mMarkerCount(0),
      isProtected(isProtected),
      mDevice(device),
      mQueue(queue),
-      mSemaphoreManager(semaphoreManager),
      mBuffer(createCommandBuffer(device, pool)),
-      mSubmission(semaphoreManager->acquire()),
+      mFenceStatus(std::make_shared<VulkanCmdFence>(VK_INCOMPLETE)),
      mAge(++sAgeCounter) {
+    VkSemaphoreCreateInfo sci{.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO};
+    vkCreateSemaphore(mDevice, &sci, VKALLOC, &mSubmission);
+
    VkFenceCreateInfo fenceCreateInfo{.sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO};
    VkExportFenceCreateInfo exportFenceCreateInfo{
        .sType = VK_STRUCTURE_TYPE_EXPORT_FENCE_CREATE_INFO,
        .handleTypes = context.getFenceExportFlags()
    };
+    fenceCreateInfo.pNext = &exportFenceCreateInfo;

-    // Necessary to guard this. Otherwise, swiftshader would throw an error.
-    if (context.getFenceExportFlags()) {
-        fenceCreateInfo.pNext = &exportFenceCreateInfo;
-    }
    vkCreateFence(device, &fenceCreateInfo, VKALLOC, &mFence);
-
-    mFenceStatus = std::make_shared<VulkanCmdFence>(mFence);
 }

 VulkanCommandBuffer::~VulkanCommandBuffer() {
+    vkDestroySemaphore(mDevice, mSubmission, VKALLOC);
    vkDestroyFence(mDevice, mFence, VKALLOC);
 }

@@ -126,15 +123,12 @@ void VulkanCommandBuffer::reset() noexcept {
    mWaitSemaphores.clear();
    mWaitSemaphoreStages.clear();
    mAge = ++sAgeCounter;
-    mSubmission = mSemaphoreManager->acquire();
-
-    // reset the fence with proper host synchronization
-    mFenceStatus->resetFence(mDevice);

    // Internally we use the VK_INCOMPLETE status to mean "not yet submitted". When this fence
    // gets, gets submitted, its status changes to VK_NOT_READY. Finally, when the GPU actually
    // finishes executing the command buffer, the status changes to VK_SUCCESS.
-    mFenceStatus = std::make_shared<VulkanCmdFence>(mFence);
+    mFenceStatus = std::make_shared<VulkanCmdFence>(VK_INCOMPLETE);
+    vkResetFences(mDevice, 1, &mFence);
 }

 void VulkanCommandBuffer::pushMarker(char const* marker) noexcept {
@@ -193,14 +187,13 @@ void VulkanCommandBuffer::begin() noexcept {
    vkBeginCommandBuffer(mBuffer, &binfo);
 }

-fvkmemory::resource_ptr<VulkanSemaphore> VulkanCommandBuffer::submit() {
+VkSemaphore VulkanCommandBuffer::submit() {
    while (mMarkerCount > 0) {
        popMarker();
    }

    vkEndCommandBuffer(mBuffer);

-    VkSemaphore submissionSemaphore = mSubmission->getVkSemaphore();
    VkSubmitInfo submitInfo{
        .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
        .waitSemaphoreCount = mWaitSemaphores.size(),
@@ -209,7 +202,7 @@ fvkmemory::resource_ptr<VulkanSemaphore> VulkanCommandBuffer::submit() {
        .commandBufferCount = 1u,
        .pCommandBuffers = &mBuffer,
        .signalSemaphoreCount = 1u,
-        .pSignalSemaphores = &submissionSemaphore,
+        .pSignalSemaphores = &mSubmission,
    };
    // add submit protection if needed
    VkProtectedSubmitInfo protectedSubmitInfo{
@@ -230,13 +223,13 @@ fvkmemory::resource_ptr<VulkanSemaphore> VulkanCommandBuffer::submit() {
                 << (s <  mWaitSemaphores.size() - 1 ? "\n" : "");
    }
    FVK_LOGI << ") "
-             << " signal=" << submissionSemaphore
+             << " signal=" << mSubmission
             << " fence=" << mFence;
 #endif

+    mFenceStatus->setStatus(VK_NOT_READY);
    UTILS_UNUSED_IN_RELEASE VkResult result =
        vkQueueSubmit(mQueue, 1, &submitInfo, mFence);
-    mFenceStatus->setStatus(VK_NOT_READY);

 #if FVK_ENABLED(FVK_DEBUG_COMMAND_BUFFER)
    if (result != VK_SUCCESS) {
@@ -249,7 +242,7 @@ fvkmemory::resource_ptr<VulkanSemaphore> VulkanCommandBuffer::submit() {
 }

 CommandBufferPool::CommandBufferPool(VulkanContext const& context, VkDevice device, VkQueue queue,
-        uint8_t queueFamilyIndex, VulkanSemaphoreManager* semaphoreManager, bool isProtected)
+        uint8_t queueFamilyIndex, bool isProtected)
    : mDevice(device),
      mRecording(INVALID) {
    VkCommandPoolCreateInfo createInfo = {
@@ -262,8 +255,8 @@ CommandBufferPool::CommandBufferPool(VulkanContext const& context, VkDevice devi
    vkCreateCommandPool(device, &createInfo, VKALLOC, &mPool);

    for (size_t i = 0; i < CAPACITY; ++i) {
-        mBuffers.emplace_back(std::make_unique<VulkanCommandBuffer>(
-                context, device, queue, mPool, semaphoreManager, isProtected));
+        mBuffers.emplace_back(
+                std::make_unique<VulkanCommandBuffer>(context, device, queue, mPool, isProtected));
    }
 }

@@ -335,10 +328,10 @@ void CommandBufferPool::update() {
    });
 }

-fvkmemory::resource_ptr<VulkanSemaphore> CommandBufferPool::flush() {
+VkSemaphore CommandBufferPool::flush() {
    // We're not recording right now.
    if (!isRecording()) {
-        return {};
+        return VK_NULL_HANDLE;
    }
    auto submitSemaphore = mBuffers[mRecording]->submit();
    mSubmitted.set(mRecording, true);
@@ -400,21 +393,16 @@ void CommandBufferPool::insertEvent(char const* marker) {
 #endif // FVK_DEBUG_GROUP_MARKERS

 VulkanCommands::VulkanCommands(VkDevice device, VkQueue queue, uint32_t queueFamilyIndex,
-        VkQueue protectedQueue, uint32_t protectedQueueFamilyIndex, VulkanContext const& context,
-        VulkanSemaphoreManager* semaphoreManager)
+        VkQueue protectedQueue, uint32_t protectedQueueFamilyIndex, VulkanContext const& context)
    : mDevice(device),
      mProtectedQueue(protectedQueue),
      mProtectedQueueFamilyIndex(protectedQueueFamilyIndex),
      mContext(context),
-      mSemaphoreManager(semaphoreManager),
-      mPool(std::make_unique<CommandBufferPool>(
-              context, device, queue, queueFamilyIndex, semaphoreManager, false)) {}
+      mPool(std::make_unique<CommandBufferPool>(context, device, queue, queueFamilyIndex, false)) {}

 void VulkanCommands::terminate() {
    mPool.reset();
    mProtectedPool.reset();
-    mLastSubmit = {};
-    mLastFenceStatus = {};
 }

 VulkanCommandBuffer& VulkanCommands::get() {
@@ -427,7 +415,7 @@ VulkanCommandBuffer& VulkanCommands::getProtected() {

    if (!mProtectedPool) {
        mProtectedPool = std::make_unique<CommandBufferPool>(mContext, mDevice, mProtectedQueue,
-                mProtectedQueueFamilyIndex, mSemaphoreManager, true);
+                mProtectedQueueFamilyIndex, true);
    }
    auto& ret = mProtectedPool->getRecording();
    return ret;
@@ -439,8 +427,8 @@ bool VulkanCommands::flush() {
        return false;
    }

-    VkSemaphore injectedDependency = mInjectedDependency;
-    fvkmemory::resource_ptr<VulkanSemaphore> dependency;
+    VkSemaphore dependency = mInjectedDependency;
+    VkSemaphore lastSubmit = mLastSubmit;
    bool hasFlushed = false;

    VkFence flushedFence = VK_NULL_HANDLE;
@@ -453,19 +441,19 @@ bool VulkanCommands::flush() {
        if (!pool || !pool->isRecording()) {
            continue;
        }
-        if (injectedDependency != VK_NULL_HANDLE) {
-            pool->waitFor(injectedDependency, mInjectedDependencyWaitStage);
+        if (dependency != VK_NULL_HANDLE) {
+            pool->waitFor(dependency, mInjectedDependencyWaitStage);
        }
-        if (mLastSubmit) {
+        if (lastSubmit != VK_NULL_HANDLE) {
            // Note that the stage we're waiting on is the fragment shader stage.  This assumes
            // that the subsequent command buffer will only depend on
            //    1) fragment output of the previous command buffer
            //    2) reading/writing of buffers (i.e. UBO) of the previous command buffer
            // Restricting the wait stages will allow for vertex work to proceed (more overlapping
            // vertex/fragment work).
-            pool->waitFor(mLastSubmit->getVkSemaphore(),
+            pool->waitFor(lastSubmit,
                    VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT | VK_PIPELINE_STAGE_TRANSFER_BIT);
-            mLastSubmit = {};
+            lastSubmit = VK_NULL_HANDLE;
        }
        flushedFence = pool->getRecording().getVkFence();
        flushedFenceStatus = pool->getRecording().getFenceStatus();
@@ -24,7 +24,6 @@
 #include "VulkanAsyncHandles.h"
 #include "VulkanConstants.h"
 #include "VulkanContext.h"
-#include "VulkanSemaphoreManager.h"
 #include "vulkan/memory/ResourcePointer.h"
 #include "vulkan/utils/StaticVector.h"

@@ -64,8 +63,8 @@ private:
 // DriverApi fence object and should not be destroyed until both the DriverApi object is freed and
 // we're done waiting on the most recent submission of the given command buffer.
 struct VulkanCommandBuffer {
-    VulkanCommandBuffer(VulkanContext const& mContext, VkDevice device, VkQueue queue,
-            VkCommandPool pool, VulkanSemaphoreManager* semaphoreManager, bool isProtected);
+    VulkanCommandBuffer(VulkanContext const& mContext,
+            VkDevice device, VkQueue queue, VkCommandPool pool, bool isProtected);

    VulkanCommandBuffer(VulkanCommandBuffer const&) = delete;
    VulkanCommandBuffer& operator=(VulkanCommandBuffer const&) = delete;
@@ -88,7 +87,7 @@ struct VulkanCommandBuffer {
    void insertEvent(char const* marker) noexcept;

    void begin() noexcept;
-    fvkmemory::resource_ptr<VulkanSemaphore> submit();
+    VkSemaphore submit();

    inline void setComplete() {
        mFenceStatus->setStatus(VK_SUCCESS);
@@ -122,11 +121,10 @@ private:
    bool const isProtected;
    VkDevice mDevice;
    VkQueue mQueue;
-    VulkanSemaphoreManager* mSemaphoreManager;
    fvkutils::StaticVector<VkSemaphore, 2> mWaitSemaphores;
    fvkutils::StaticVector<VkPipelineStageFlags, 2> mWaitSemaphoreStages;
    VkCommandBuffer mBuffer;
-    fvkmemory::resource_ptr<VulkanSemaphore> mSubmission;
+    VkSemaphore mSubmission;
    VkFence mFence;
    std::shared_ptr<VulkanCmdFence> mFenceStatus;
    std::vector<fvkmemory::resource_ptr<Resource>> mResources;
@@ -138,14 +136,14 @@ struct CommandBufferPool {
    static constexpr int8_t INVALID = -1;

    CommandBufferPool(VulkanContext const& context, VkDevice device, VkQueue queue,
-            uint8_t queueFamilyIndex, VulkanSemaphoreManager* semaphoreManager, bool isProtected);
+            uint8_t queueFamilyIndex, bool isProtected);
    ~CommandBufferPool();

    VulkanCommandBuffer& getRecording();

    void gc();
    void update();
-    fvkmemory::resource_ptr<VulkanSemaphore> flush();
+    VkSemaphore flush();
    void wait();
    void waitFor(VkSemaphore previousAction, VkPipelineStageFlags waitStage);

@@ -206,7 +204,7 @@ class VulkanCommands {
 public:
    VulkanCommands(VkDevice device, VkQueue queue, uint32_t queueFamilyIndex,
            VkQueue protectedQueue, uint32_t protectedQueueFamilyIndex,
-            VulkanContext const& context, VulkanSemaphoreManager* semaphoreManager);
+            VulkanContext const& context);

    void terminate();

@@ -224,10 +222,10 @@ public:
    // Returns the "rendering finished" semaphore for the most recent flush and removes
    // it from the existing dependency chain. This is especially useful for setting up
    // vkQueuePresentKHR.
-    fvkmemory::resource_ptr<VulkanSemaphore> acquireFinishedSignal() {
-        fvkmemory::resource_ptr<VulkanSemaphore> sem = mLastSubmit;
-        mLastSubmit = {};
-        return sem;
+    VkSemaphore acquireFinishedSignal() {
+        VkSemaphore ret = mLastSubmit;
+        mLastSubmit = VK_NULL_HANDLE;
+        return ret;
    }

    VkFence getMostRecentFence() {
@@ -268,13 +266,12 @@ private:
    // For defered initialization if/when we need protected content
    uint32_t const mProtectedQueueFamilyIndex;
    VulkanContext const& mContext;
-    VulkanSemaphoreManager* mSemaphoreManager;

    std::unique_ptr<CommandBufferPool> mPool;
    std::unique_ptr<CommandBufferPool> mProtectedPool;

    VkSemaphore mInjectedDependency = VK_NULL_HANDLE;
-    fvkmemory::resource_ptr<VulkanSemaphore> mLastSubmit;
+    VkSemaphore mLastSubmit = VK_NULL_HANDLE;

    VkFence mLastFence = VK_NULL_HANDLE;
    std::shared_ptr<VulkanCmdFence> mLastFenceStatus;
@@ -43,8 +43,6 @@
 #include <set>  // For VulkanDriver::debugCommandBegin
 #endif

-#include <chrono>
-
 using namespace bluevk;

 #if defined(__clang__)
@@ -224,10 +222,9 @@ VulkanDriver::VulkanDriver(VulkanPlatform* platform, VulkanContext& context,
      mAllocator(createAllocator(mPlatform->getInstance(), mPlatform->getPhysicalDevice(),
              mPlatform->getDevice())),
      mContext(context),
-      mSemaphoreManager(mPlatform->getDevice(), &mResourceManager),
      mCommands(mPlatform->getDevice(), mPlatform->getGraphicsQueue(),
              mPlatform->getGraphicsQueueFamilyIndex(), mPlatform->getProtectedGraphicsQueue(),
-              mPlatform->getProtectedGraphicsQueueFamilyIndex(), mContext, &mSemaphoreManager),
+              mPlatform->getProtectedGraphicsQueueFamilyIndex(), mContext),
      mPipelineLayoutCache(mPlatform->getDevice()),
      mPipelineCache(mPlatform->getDevice()),
      mStagePool(mAllocator, &mResourceManager, &mCommands, &mContext.getPhysicalDeviceLimits()),
@@ -322,9 +319,8 @@ ShaderModel VulkanDriver::getShaderModel() const noexcept {
 #endif
 }

-utils::FixedCapacityVector<ShaderLanguage> VulkanDriver::getShaderLanguages(
-        ShaderLanguage /*prefferedLanguage*/) const noexcept {
-    return { ShaderLanguage::SPIRV };
+ShaderLanguage VulkanDriver::getShaderLanguage() const noexcept {
+    return ShaderLanguage::SPIRV;
 }

 void VulkanDriver::terminate() {
@@ -369,9 +365,6 @@ void VulkanDriver::terminate() {
    // reclaimed, as they perform cleanup within the stage pool.
    mStagePool.terminate();

-    // By this point, all of the VkSemaphores should have been returned to the pool.
-    mSemaphoreManager.terminate();
-
 #if FVK_ENABLED(FVK_DEBUG_RESOURCE_LEAK)
    mResourceManager.print();
 #endif
@@ -483,21 +476,6 @@ void VulkanDriver::updateDescriptorSetTexture(
    }
 }

-void VulkanDriver::copyToMemoryMappedBuffer(MemoryMappedBufferHandle mmbh, size_t offset,
-        BufferDescriptor&& data) {
-    FVK_SYSTRACE_SCOPE();
-    auto mmb = resource_ptr<VulkanMemoryMappedBuffer>::cast(&mResourceManager, mmbh);
-
-    assert_invariant(any(mmb->access & MapBufferAccessFlags::WRITE_BIT));
-    assert_invariant(offset + data.size <= mmb->size);
-
-    // TODO: this isa zero-effort implementation of copyToMemoryMappedBuffer(), where we just
-    //       call updateBufferObject(). This could be a fallback implementation for when
-    //       shared memory is not available.
-    //       On UMA systems, this should just be a memcpy into the memory-mapped buffer.
-    updateBufferObject(mmb->boh, std::move(data), mmb->offset + offset);
-}
-
 void VulkanDriver::flush(int) {
    FVK_SYSTRACE_SCOPE();
    endCommandRecording();
@@ -524,7 +502,7 @@ void VulkanDriver::finish(int dummy) {

 void VulkanDriver::createRenderPrimitiveR(Handle<HwRenderPrimitive> rph,
        Handle<HwVertexBuffer> vbh, Handle<HwIndexBuffer> ibh,
-        PrimitiveType pt, utils::CString&& tag) {
+        PrimitiveType pt, utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    auto vb = resource_ptr<VulkanVertexBuffer>::cast(&mResourceManager, vbh);
    auto ib = resource_ptr<VulkanIndexBuffer>::cast(&mResourceManager, ibh);
@@ -543,7 +521,7 @@ void VulkanDriver::destroyRenderPrimitive(Handle<HwRenderPrimitive> rph) {
 }

 void VulkanDriver::createVertexBufferInfoR(Handle<HwVertexBufferInfo> vbih, uint8_t bufferCount,
-        uint8_t attributeCount, AttributeArray attributes, utils::CString&& tag) {
+        uint8_t attributeCount, AttributeArray attributes, utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    auto vbi = resource_ptr<VulkanVertexBufferInfo>::make(&mResourceManager, vbih, bufferCount,
            attributeCount, attributes);
@@ -561,7 +539,7 @@ void VulkanDriver::destroyVertexBufferInfo(Handle<HwVertexBufferInfo> vbih) {
 }

 void VulkanDriver::createVertexBufferR(Handle<HwVertexBuffer> vbh, uint32_t vertexCount,
-        Handle<HwVertexBufferInfo> vbih, utils::CString&& tag) {
+        Handle<HwVertexBufferInfo> vbih, utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    auto vbi = resource_ptr<VulkanVertexBufferInfo>::cast(&mResourceManager, vbih);
    auto vb = resource_ptr<VulkanVertexBuffer>::make(&mResourceManager, vbh, mContext, mStagePool,
@@ -580,7 +558,7 @@ void VulkanDriver::destroyVertexBuffer(Handle<HwVertexBuffer> vbh) {
 }

 void VulkanDriver::createIndexBufferR(Handle<HwIndexBuffer> ibh, ElementType elementType,
-        uint32_t indexCount, BufferUsage usage, utils::CString&& tag) {
+        uint32_t indexCount, BufferUsage usage, utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    auto elementSize = (uint8_t) getElementTypeSize(elementType);
    auto ib = resource_ptr<VulkanIndexBuffer>::make(&mResourceManager, ibh, mContext, mAllocator,
@@ -599,10 +577,10 @@ void VulkanDriver::destroyIndexBuffer(Handle<HwIndexBuffer> ibh) {
 }

 void VulkanDriver::createBufferObjectR(Handle<HwBufferObject> boh, uint32_t byteCount,
-        BufferObjectBinding bindingType, BufferUsage usage, utils::CString&& tag) {
+        BufferObjectBinding bindingType, BufferUsage usage, utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    auto bo = resource_ptr<VulkanBufferObject>::make(&mResourceManager, boh, mContext, mAllocator,
-            mStagePool, mBufferCache, byteCount, bindingType, usage);
+            mStagePool, mBufferCache, byteCount, bindingType);
    bo.inc();
    mResourceManager.associateHandle(boh.getId(), std::move(tag));
 }
@@ -618,7 +596,7 @@ void VulkanDriver::destroyBufferObject(Handle<HwBufferObject> boh) {

 void VulkanDriver::createTextureR(Handle<HwTexture> th, SamplerType target, uint8_t levels,
        TextureFormat format, uint8_t samples, uint32_t w, uint32_t h, uint32_t depth,
-        TextureUsage usage, utils::CString&& tag) {
+        TextureUsage usage, utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    auto texture = resource_ptr<VulkanTexture>::make(&mResourceManager, th, mPlatform->getDevice(),
            mPlatform->getPhysicalDevice(), mContext, mAllocator, &mResourceManager, &mCommands,
@@ -635,7 +613,7 @@ void VulkanDriver::createTextureR(Handle<HwTexture> th, SamplerType target, uint
 }

 void VulkanDriver::createTextureViewR(Handle<HwTexture> th, Handle<HwTexture> srch,
-        uint8_t baseLevel, uint8_t levelCount, utils::CString&& tag) {
+        uint8_t baseLevel, uint8_t levelCount, utils::CString tag) {
    auto src = resource_ptr<VulkanTexture>::cast(&mResourceManager, srch);
    auto texture = resource_ptr<VulkanTexture>::make(&mResourceManager, th, mPlatform->getDevice(),
            mPlatform->getPhysicalDevice(), mContext, mAllocator, &mCommands, src, baseLevel,
@@ -646,7 +624,7 @@ void VulkanDriver::createTextureViewR(Handle<HwTexture> th, Handle<HwTexture> sr

 void VulkanDriver::createTextureViewSwizzleR(Handle<HwTexture> th, Handle<HwTexture> srch,
        backend::TextureSwizzle r, backend::TextureSwizzle g, backend::TextureSwizzle b,
-        backend::TextureSwizzle a, utils::CString&& tag) {
+        backend::TextureSwizzle a, utils::CString tag) {
    TextureSwizzle const swizzleArray[] = { r, g, b, a };
    VkComponentMapping const swizzle = fvkutils::getSwizzleMap(swizzleArray);
    auto src = resource_ptr<VulkanTexture>::cast(&mResourceManager, srch);
@@ -658,7 +636,7 @@ void VulkanDriver::createTextureViewSwizzleR(Handle<HwTexture> th, Handle<HwText

 void VulkanDriver::createTextureExternalImage2R(Handle<HwTexture> th, backend::SamplerType target,
        backend::TextureFormat format, uint32_t width, uint32_t height, backend::TextureUsage usage,
-        Platform::ExternalImageHandleRef externalImage, utils::CString&& tag) {
+        Platform::ExternalImageHandleRef externalImage, utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    auto metadata = mPlatform->extractExternalImageMetadata(externalImage);

@@ -709,7 +687,7 @@ void VulkanDriver::createTextureExternalImage2R(Handle<HwTexture> th, backend::S

 void VulkanDriver::createTextureExternalImageR(Handle<HwTexture> th, backend::SamplerType target,
        backend::TextureFormat format, uint32_t width, uint32_t height, backend::TextureUsage usage,
-        void* externalImage, utils::CString&& tag) {
+        void* externalImage, utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    assert_invariant(false && "Not supported in Vulkan backend");
    // not supported in this backend
@@ -717,14 +695,14 @@ void VulkanDriver::createTextureExternalImageR(Handle<HwTexture> th, backend::Sa

 void VulkanDriver::createTextureExternalImagePlaneR(Handle<HwTexture> th,
        backend::TextureFormat format, uint32_t width, uint32_t height, backend::TextureUsage usage,
-        void* image, uint32_t plane, utils::CString&& tag) {
+        void* image, uint32_t plane, utils::CString tag) {
    assert_invariant(false && "Not supported in Vulkan backend");
 }

 void VulkanDriver::importTextureR(Handle<HwTexture> th, intptr_t id,
        SamplerType target, uint8_t levels,
        TextureFormat format, uint8_t samples, uint32_t w, uint32_t h, uint32_t depth,
-        TextureUsage usage, utils::CString&& tag) {
+        TextureUsage usage, utils::CString tag) {
    // not supported in this backend
    assert_invariant(false && "Not supported in Vulkan backend");
    mResourceManager.associateHandle(th.getId(), std::move(tag));
@@ -740,7 +718,7 @@ void VulkanDriver::destroyTexture(Handle<HwTexture> th) {
    mExternalImageManager.removeExternallySampledTexture(texture);
 }

-void VulkanDriver::createProgramR(Handle<HwProgram> ph, Program&& program, utils::CString&& tag) {
+void VulkanDriver::createProgramR(Handle<HwProgram> ph, Program&& program, utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    auto vprogram = resource_ptr<VulkanProgram>::make(&mResourceManager, ph, mPlatform->getDevice(),
            program);
@@ -756,7 +734,7 @@ void VulkanDriver::destroyProgram(Handle<HwProgram> ph) {
    vprogram.dec();
 }

-void VulkanDriver::createDefaultRenderTargetR(Handle<HwRenderTarget> rth, utils::CString&& tag) {
+void VulkanDriver::createDefaultRenderTargetR(Handle<HwRenderTarget> rth, utils::CString tag) {
    assert_invariant(mDefaultRenderTarget); // Default render target should already exist.

    auto renderTarget = resource_ptr<VulkanRenderTarget>::make(&mResourceManager, rth,
@@ -769,7 +747,7 @@ void VulkanDriver::createDefaultRenderTargetR(Handle<HwRenderTarget> rth, utils:
 void VulkanDriver::createRenderTargetR(Handle<HwRenderTarget> rth,
        TargetBufferFlags targets, uint32_t width, uint32_t height, uint8_t samples,
        uint8_t layerCount, MRT color, TargetBufferInfo depth, TargetBufferInfo stencil,
-        utils::CString&& tag) {
+        utils::CString tag) {

    FVK_SYSTRACE_SCOPE();

@@ -846,7 +824,7 @@ void VulkanDriver::destroyRenderTarget(Handle<HwRenderTarget> rth) {
    }
 }

-void VulkanDriver::createFenceR(Handle<HwFence> fh, utils::CString&& tag) {
+void VulkanDriver::createFenceR(Handle<HwFence> fh, utils::CString tag) {
    VulkanCommandBuffer* cmdbuf;
    if (mCurrentRenderPass.commandBuffer) {
        cmdbuf = mCurrentRenderPass.commandBuffer;
@@ -857,11 +835,11 @@ void VulkanDriver::createFenceR(Handle<HwFence> fh, utils::CString&& tag) {
    // it with appropriate VulkanCmdFence, which is associated with the current, recording command
    // buffer.
    auto fence = resource_ptr<VulkanFence>::cast(&mResourceManager, fh);
-    fence->setFence(cmdbuf->getFenceStatus());
+    fence->fence = cmdbuf->getFenceStatus();
    mResourceManager.associateHandle(fh.getId(), std::move(tag));
 }

-void VulkanDriver::createSyncR(Handle<HwSync> sh, utils::CString&& tag) {
+void VulkanDriver::createSyncR(Handle<HwSync> sh, utils::CString tag) {
    auto sync = resource_ptr<VulkanSync>::cast(&mResourceManager, sh);
    VkFence fence = VK_NULL_HANDLE;
    std::shared_ptr<VulkanCmdFence> fenceStatus;
@@ -892,7 +870,7 @@ void VulkanDriver::createSyncR(Handle<HwSync> sh, utils::CString&& tag) {
 }

 void VulkanDriver::createSwapChainR(Handle<HwSwapChain> sch, void* nativeWindow, uint64_t flags,
-        utils::CString&& tag) {
+        utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    // Running gc() to guard against an edge case where the old swapchains need to have been
    // destroyed before the new swapchain can be created. Otherwise, we would fail
@@ -921,7 +899,7 @@ void VulkanDriver::createSwapChainR(Handle<HwSwapChain> sch, void* nativeWindow,
 }

 void VulkanDriver::createSwapChainHeadlessR(Handle<HwSwapChain> sch, uint32_t width,
-        uint32_t height, uint64_t flags, utils::CString&& tag) {
+        uint32_t height, uint64_t flags, utils::CString tag) {
    if ((flags & backend::SWAP_CHAIN_CONFIG_SRGB_COLORSPACE) != 0 && !isSRGBSwapChainSupported()) {
        FVK_LOGW << "sRGB swapchain requested, but Platform does not support it";
        flags = flags | ~(backend::SWAP_CHAIN_CONFIG_SRGB_COLORSPACE);
@@ -934,13 +912,13 @@ void VulkanDriver::createSwapChainHeadlessR(Handle<HwSwapChain> sch, uint32_t wi
    mResourceManager.associateHandle(sch.getId(), std::move(tag));
 }

-void VulkanDriver::createTimerQueryR(Handle<HwTimerQuery> tqh, utils::CString&& tag) {
+void VulkanDriver::createTimerQueryR(Handle<HwTimerQuery> tqh, utils::CString tag) {
    // nothing to do, timer query was constructed in createTimerQueryS
    mResourceManager.associateHandle(tqh.getId(), std::move(tag));
 }

 void VulkanDriver::createDescriptorSetLayoutR(Handle<HwDescriptorSetLayout> dslh,
-        backend::DescriptorSetLayout&& info, utils::CString&& tag) {
+        backend::DescriptorSetLayout&& info, utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    auto layout = mDescriptorSetLayoutCache.createLayout(dslh, std::move(info));
    layout.inc();
@@ -948,7 +926,7 @@ void VulkanDriver::createDescriptorSetLayoutR(Handle<HwDescriptorSetLayout> dslh
 }

 void VulkanDriver::createDescriptorSetR(Handle<HwDescriptorSet> dsh,
-        Handle<HwDescriptorSetLayout> dslh, utils::CString&& tag) {
+        Handle<HwDescriptorSetLayout> dslh, utils::CString tag) {
    FVK_SYSTRACE_SCOPE();
    fvkmemory::resource_ptr<VulkanDescriptorSetLayout> layout =
            fvkmemory::resource_ptr<VulkanDescriptorSetLayout>::cast(&mResourceManager, dslh);
@@ -962,16 +940,6 @@ void VulkanDriver::createDescriptorSetR(Handle<HwDescriptorSet> dsh,
    mResourceManager.associateHandle(dsh.getId(), std::move(tag));
 }

-void VulkanDriver::mapBufferR(MemoryMappedBufferHandle mmbh,
-        BufferObjectHandle boh, size_t offset,
-        size_t size, MapBufferAccessFlags access, utils::CString&& tag) {
-    FVK_SYSTRACE_SCOPE();
-    auto mmb = resource_ptr<VulkanMemoryMappedBuffer>::make(&mResourceManager, mmbh,
-            boh, offset, size, access);
-    mmb.inc();
-    mResourceManager.associateHandle(mmbh.getId(), std::move(tag));
-}
-
 Handle<HwVertexBufferInfo> VulkanDriver::createVertexBufferInfoS() noexcept {
    return mResourceManager.allocHandle<VulkanVertexBufferInfo>();
 }
@@ -1070,19 +1038,6 @@ Handle<HwDescriptorSet> VulkanDriver::createDescriptorSetS() noexcept {
    return mResourceManager.allocHandle<VulkanDescriptorSet>();
 }

-MemoryMappedBufferHandle VulkanDriver::mapBufferS() noexcept {
-    return mResourceManager.allocHandle<VulkanMemoryMappedBuffer>();
-}
-
-void VulkanDriver::unmapBuffer(MemoryMappedBufferHandle mmbh) {
-    if (!mmbh) {
-        return;
-    }
-    auto mmb = resource_ptr<VulkanMemoryMappedBuffer>::cast(&mResourceManager, mmbh);
-    mmb.dec();
-}
-
-
 void VulkanDriver::destroySwapChain(Handle<HwSwapChain> sch) {
    if (!sch) {
        return;
@@ -1158,30 +1113,29 @@ void VulkanDriver::destroyFence(Handle<HwFence> fh) {
    fence.dec();
 }

-FenceStatus VulkanDriver::getFenceStatus(Handle<HwFence> const fh) {
-    return fenceWait(fh, 0);
-}
-
-FenceStatus VulkanDriver::fenceWait(FenceHandle const fh, uint64_t const timeout) {
+FenceStatus VulkanDriver::getFenceStatus(Handle<HwFence> fh) {
    auto fence = resource_ptr<VulkanFence>::cast(&mResourceManager, fh);

-    // we have to take into account that the STL's wait_for() actually works with
-    // time_points relative to steady_clock::now() internally.
-    using namespace std::chrono;
-    auto const now = steady_clock::now();
-    steady_clock::time_point until = steady_clock::time_point::max();
-    if (now <= steady_clock::time_point::max() - nanoseconds(timeout)) {
-        until = now + nanoseconds(timeout);
-    }
-
-    std::shared_ptr const cmdfence = fence->wait(until);
+    auto& cmdfence = fence->fence;
    if (!cmdfence) {
+        // If wait is called before a fence actually exists, we return timeout.  This matches the
+        // current behavior in OpenGLDriver, but we should eventually reconsider a different error
+        // code.
        return FenceStatus::TIMEOUT_EXPIRED;
    }

-    // now we are holding a reference to our VulkanCmdFence, so we know it can't
-    // disappear while we wait
-    return cmdfence->wait(mPlatform->getDevice(), timeout, until);
+    // Internally we use the VK_INCOMPLETE status to mean "not yet submitted".
+    // When this fence gets submitted, its status changes to VK_NOT_READY.
+    if (cmdfence->getStatus() == VK_SUCCESS) {
+        return FenceStatus::CONDITION_SATISFIED;
+    }
+
+
+    // Two other states are possible:
+    //   - VK_INCOMPLETE: the corresponding buffer has not yet been submitted.
+    //   - VK_NOT_READY: the buffer has been submitted but not yet signaled.
+    //     In either case, we return TIMEOUT_EXPIRED to indicate the fence has not been signaled.
+    return FenceStatus::TIMEOUT_EXPIRED;
 }

 void VulkanDriver::getPlatformSync(Handle<HwSync> sh, CallbackHandler* handler,
@@ -28,7 +28,6 @@
 #include "VulkanQueryManager.h"
 #include "VulkanReadPixels.h"
 #include "VulkanSamplerCache.h"
-#include "VulkanSemaphoreManager.h"
 #include "VulkanStagePool.h"
 #include "VulkanYcbcrConversionCache.h"
 #include "vulkan/VulkanDescriptorSetCache.h"
@@ -44,7 +43,6 @@
 #include "DriverBase.h"
 #include "private/backend/Driver.h"

-#include <utils/FixedCapacityVector.h>
 #include <utils/Allocator.h>
 #include <utils/compiler.h>

@@ -102,8 +100,7 @@ private:
    Dispatcher getDispatcher() const noexcept final;

    ShaderModel getShaderModel() const noexcept final;
-    utils::FixedCapacityVector<ShaderLanguage> getShaderLanguages(
-            ShaderLanguage preferredLanguage) const noexcept final;
+    ShaderLanguage getShaderLanguage() const noexcept final;

    template<typename T>
    friend class ConcreteDispatcher;
@@ -142,7 +139,6 @@ private:

    VulkanContext& mContext;

-    VulkanSemaphoreManager mSemaphoreManager;
    VulkanCommands mCommands;
    VulkanPipelineLayoutCache mPipelineLayoutCache;
    VulkanPipelineCache mPipelineCache;
@@ -40,18 +40,18 @@ namespace filament::backend {

 namespace {

-inline VulkanBufferBinding getBufferObjectBinding(BufferObjectBinding bindingType) noexcept {
+inline VulkanBufferUsage getBufferObjectUsage(BufferObjectBinding bindingType) noexcept {
    switch (bindingType) {
        case BufferObjectBinding::VERTEX:
-            return VulkanBufferBinding::VERTEX;
+            return VulkanBufferUsage::VERTEX;
        case BufferObjectBinding::UNIFORM:
-            return VulkanBufferBinding::UNIFORM;
+            return VulkanBufferUsage::UNIFORM;
        case BufferObjectBinding::SHADER_STORAGE:
-            return VulkanBufferBinding::SHADER_STORAGE;
+            return VulkanBufferUsage::SHADER_STORAGE;
            // when adding more buffer-types here, make sure to update VulkanBuffer::loadFromCpu()
            // if necessary.
    }
-    return VulkanBufferBinding::UNKNOWN;
+    return VulkanBufferUsage::UNKNOWN;
 }

 void flipVertically(VkViewport* rect, uint32_t framebufferHeight) {
@@ -614,11 +614,10 @@ void VulkanVertexBuffer::setBuffer(fvkmemory::resource_ptr<VulkanBufferObject> b

 VulkanBufferObject::VulkanBufferObject(VulkanContext const& context, VmaAllocator allocator,
        VulkanStagePool& stagePool, VulkanBufferCache& bufferCache, uint32_t byteCount,
-        BufferObjectBinding bindingType, BufferUsage usage)
+        BufferObjectBinding bindingType)
    : HwBufferObject(byteCount),
      bindingType(bindingType),
-      mBuffer(context, allocator, stagePool, bufferCache, getBufferObjectBinding(bindingType),
-              usage, byteCount) {}
+      mBuffer(context, allocator, stagePool, bufferCache, getBufferObjectUsage(bindingType), byteCount) {}

 VulkanRenderPrimitive::VulkanRenderPrimitive(PrimitiveType pt,
        fvkmemory::resource_ptr<VulkanVertexBuffer> vb,
@@ -225,17 +225,6 @@ private:
    fvkutils::UniformBufferBitmask mUboMask;
 };

-struct VulkanMemoryMappedBuffer : public HwMemoryMappedBuffer, Resource {
-    VulkanMemoryMappedBuffer(BufferObjectHandle boh, size_t const offset,
-            size_t const size, MapBufferAccessFlags const access)
-        : boh(boh), access(access), size(size), offset(offset) {
-    }
-    BufferObjectHandle boh{};
-    MapBufferAccessFlags access{};
-    uint32_t size = 0;
-    uint32_t offset = 0;
-};
-
 using PushConstantNameArray = utils::FixedCapacityVector<char const*>;
 using PushConstantNameByStage = std::array<PushConstantNameArray, Program::SHADER_TYPE_COUNT>;

@@ -477,8 +466,8 @@ struct VulkanIndexBuffer : public HwIndexBuffer, fvkmemory::Resource {
            uint32_t indexCount)
        : HwIndexBuffer(elementSize, indexCount),
          indexType(elementSize == 2 ? VK_INDEX_TYPE_UINT16 : VK_INDEX_TYPE_UINT32),
-          mBuffer(context, allocator, stagePool, bufferCache, VulkanBufferBinding::INDEX,
-                  BufferUsage::STATIC, elementSize * indexCount) {}
+          mBuffer(context, allocator, stagePool, bufferCache, VulkanBufferUsage::INDEX,
+                  elementSize * indexCount) {}

    inline void loadFromCpu(VulkanCommandBuffer& commands, const void* cpuData, uint32_t byteOffset,
            uint32_t numBytes) {
@@ -496,7 +485,7 @@ private:
 struct VulkanBufferObject : public HwBufferObject, fvkmemory::Resource {
    VulkanBufferObject(VulkanContext const& context, VmaAllocator allocator,
            VulkanStagePool& stagePool, VulkanBufferCache& bufferCache, uint32_t byteCount,
-            BufferObjectBinding bindingType, BufferUsage usage);
+            BufferObjectBinding bindingType);

    inline void loadFromCpu(VulkanCommandBuffer& commands, const void* cpuData, uint32_t byteOffset,
            uint32_t numBytes) {
@@ -39,7 +39,7 @@ VK_DEFINE_HANDLE(VmaPool)

 namespace filament::backend {

-enum class VulkanBufferBinding : uint8_t {
+enum class VulkanBufferUsage : uint8_t {
    UNKNOWN,
    VERTEX,
    INDEX,
@@ -52,7 +52,7 @@ struct VulkanGpuBuffer {
    VmaAllocation vmaAllocation = VK_NULL_HANDLE;
    VmaAllocationInfo allocationInfo;
    uint32_t numBytes = 0;
-    VulkanBufferBinding binding = VulkanBufferBinding::UNKNOWN;
+    VulkanBufferUsage usage = VulkanBufferUsage::UNKNOWN;
 };

 } // namespace filament::backend
@@ -1,29 +0,0 @@
-/*
- * Copyright (C) 2025 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "vulkan/VulkanSemaphore.h"
-#include "vulkan/VulkanSemaphoreManager.h"
-
-namespace filament::backend {
-
-VulkanSemaphore::VulkanSemaphore(VulkanSemaphoreManager* manager, VkSemaphore semaphore)
-    : mManager(manager), mSemaphore(semaphore) {}
-
-VulkanSemaphore::~VulkanSemaphore() {
-    mManager->recycle(mSemaphore);
-}
-
-} // namespace filament::backend
@@ -1,42 +0,0 @@
-/*
- * Copyright (C) 2025 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_VULKAN_VULKANSEMAPHORE_H
-#define TNT_FILAMENT_BACKEND_VULKAN_VULKANSEMAPHORE_H
-
-#include "memory/Resource.h"
-
-#include <bluevk/BlueVK.h>
-
-namespace filament::backend {
-
-class VulkanSemaphoreManager;
-
-struct VulkanSemaphore : public fvkmemory::Resource {
-public:
-    VulkanSemaphore(VulkanSemaphoreManager* manager, VkSemaphore semaphore);
-    ~VulkanSemaphore();
-
-    VkSemaphore getVkSemaphore() const { return mSemaphore; }
-
-private:
-    VulkanSemaphoreManager* mManager;
-    VkSemaphore mSemaphore;
-};
-
-} // namespace filament::backend
-
-#endif // TNT_FILAMENT_BACKEND_VULKAN_VULKANSEMAPHORE_H
@@ -1,70 +0,0 @@
-/*
- * Copyright (C) 2025 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "VulkanSemaphoreManager.h"
-
-#include "VulkanConstants.h"
-
-using namespace bluevk;
-
-namespace {
-constexpr size_t INITIAL_POOL_SIZE = FVK_MAX_COMMAND_BUFFERS;
-
-VkSemaphore createSemaphore(VkDevice device) {
-    VkSemaphore semaphore;
-    VkSemaphoreCreateInfo semaphoreInfo = {
-        .sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO,
-    };
-    vkCreateSemaphore(device, &semaphoreInfo, VKALLOC, &semaphore);
-    return semaphore;
-}
-
-} // namespace
-
-namespace filament::backend {
-
-VulkanSemaphoreManager::VulkanSemaphoreManager(VkDevice device,
-        fvkmemory::ResourceManager* resourceManager)
-    : mDevice(device),
-      mResourceManager(resourceManager) {
-    for (size_t i= 0; i < INITIAL_POOL_SIZE; ++i) {
-        mPool.push_back(createSemaphore(mDevice));
-    }
-}
-
-void VulkanSemaphoreManager::terminate() {
-    for (VkSemaphore semaphore : mPool) {
-        vkDestroySemaphore(mDevice, semaphore, VKALLOC);
-    }
-    mPool.clear();
-}
-
-VulkanSemaphoreManager::Semaphore VulkanSemaphoreManager::acquire() {
-    VkSemaphore semaphore;
-    if (!mPool.empty()) {
-        semaphore = mPool.back();
-        mPool.pop_back();
-    } else {
-        semaphore = createSemaphore(mDevice);
-    }
-    return Semaphore::construct(mResourceManager, this, semaphore);
-}
-
-void VulkanSemaphoreManager::recycle(VkSemaphore semaphore) {
-    mPool.push_back(semaphore);
-}
-
-} // namespace filament::backend
@@ -1,51 +0,0 @@
-/*
- * Copyright (C) 2025 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef TNT_FILAMENT_BACKEND_VULKAN_VULKANSEMAPHOREMANAGER_H
-#define TNT_FILAMENT_BACKEND_VULKAN_VULKANSEMAPHOREMANAGER_H
-
-#include "vulkan/VulkanSemaphore.h"
-#include "vulkan/memory/ResourceManager.h"
-#include "vulkan/memory/ResourcePointer.h"
-
-#include <bluevk/BlueVK.h>
-
-#include <vector>
-
-namespace filament::backend {
-
-class VulkanSemaphoreManager {
-public:
-    using Semaphore = fvkmemory::resource_ptr<VulkanSemaphore>;
-
-    VulkanSemaphoreManager(VkDevice device, fvkmemory::ResourceManager* resourceManager);
-    ~VulkanSemaphoreManager() = default;
-
-    void terminate();
-    Semaphore acquire();
-
-private:
-    friend struct VulkanSemaphore;
-    void recycle(VkSemaphore semaphore);
-
-    VkDevice mDevice;
-    fvkmemory::ResourceManager* mResourceManager;
-    std::vector<VkSemaphore> mPool;
-};
-
-} // namespace filament::backend
-
-#endif // TNT_FILAMENT_BACKEND_VULKAN_VULKANSEMAPHOREMANAGER_H
@@ -59,10 +59,7 @@ VulkanSwapChain::~VulkanSwapChain() {

    mColors = {};
    mDepth = {};
-    for (auto& semaphore : mFinishedDrawing) {
-        semaphore = {};
-    }
-    mFinishedDrawing.clear();
+
    mPlatform->destroy(swapChain);
 }

@@ -70,17 +67,9 @@ void VulkanSwapChain::update() {
    mColors.clear();

    auto const bundle = mPlatform->getSwapChainBundle(swapChain);
-    size_t const swapChainCount = bundle.colors.size();
    mColors.reserve(bundle.colors.size());
    VkDevice const device = mPlatform->getDevice();

-    mFinishedDrawing.clear();
-    mFinishedDrawing.reserve(swapChainCount);
-    mFinishedDrawing.resize(swapChainCount);
-    for (size_t i = 0; i < swapChainCount; ++i) {
-        mFinishedDrawing[i] = {};
-    }
-
    TextureUsage depthUsage = TextureUsage::DEPTH_ATTACHMENT;
    TextureUsage colorUsage = TextureUsage::COLOR_ATTACHMENT;
    if (bundle.isProtected) {
@@ -121,10 +110,8 @@ void VulkanSwapChain::present(DriverBase& driver) {

    // We only present if it is not headless. No-op for headless.
    if (!mHeadless) {
-        auto finishedDrawing = mCommands->acquireFinishedSignal();
-        mFinishedDrawing[mCurrentSwapIndex] = finishedDrawing;
-        VkResult const result =
-                mPlatform->present(swapChain, mCurrentSwapIndex, finishedDrawing->getVkSemaphore());
+        VkSemaphore const finishedDrawing = mCommands->acquireFinishedSignal();
+        VkResult const result = mPlatform->present(swapChain, mCurrentSwapIndex, finishedDrawing);
        FILAMENT_CHECK_POSTCONDITION(result == VK_SUCCESS || result == VK_SUBOPTIMAL_KHR ||
                result == VK_ERROR_OUT_OF_DATE_KHR)
                << "Cannot present in swapchain. error=" << static_cast<int32_t>(result);
@@ -136,9 +123,9 @@ void VulkanSwapChain::present(DriverBase& driver) {

    if (frameScheduled.callback) {
        driver.scheduleCallback(frameScheduled.handler,
-                [callback = frameScheduled.callback]() {
+                [callback = std::move(frameScheduled.callback)]() {
                    PresentCallable noop = PresentCallable(PresentCallable::noopPresent, nullptr);
-                    callback->operator()(noop);
+                    callback(noop);
                });
    }
 }
@@ -162,7 +149,6 @@ void VulkanSwapChain::acquire(bool& resized) {
    VulkanPlatform::ImageSyncData imageSyncData;
    VkResult const result = mPlatform->acquire(swapChain, &imageSyncData);
    mCurrentSwapIndex = imageSyncData.imageIndex;
-    mFinishedDrawing[mCurrentSwapIndex] = {};
    FILAMENT_CHECK_POSTCONDITION(result == VK_SUCCESS || result == VK_SUBOPTIMAL_KHR)
            << "Cannot acquire in swapchain. error=" << static_cast<int32_t>(result);
    if (imageSyncData.imageReadySemaphore != VK_NULL_HANDLE) {
@@ -29,7 +29,6 @@
 #include <bluevk/BlueVK.h>
 #include <utils/FixedCapacityVector.h>

-#include <memory>

 using namespace bluevk;

@@ -83,13 +82,8 @@ struct VulkanSwapChain : public HwSwapChain, fvkmemory::Resource {

    inline void setFrameScheduledCallback(CallbackHandler* handler,
            FrameScheduledCallback&& callback) noexcept {
-        if (!callback) {
-            frameScheduled.handler = nullptr;
-            frameScheduled.callback.reset();
-            return;
-        }
        frameScheduled.handler = handler;
-        frameScheduled.callback = std::make_shared<FrameScheduledCallback>(std::move(callback));
+        frameScheduled.callback = std::move(callback);
    }

 private:
@@ -110,13 +104,12 @@ private:
    // These fields store a callback to notify the client that Filament is commiting a frame.
    struct {
        CallbackHandler* handler = nullptr;
-        std::shared_ptr<FrameScheduledCallback> callback = nullptr;
+        FrameScheduledCallback callback;
    } frameScheduled;

    // We create VulkanTextures based on VkImages. VulkanTexture has facilities for doing layout
    // transitions, which are useful here.
    utils::FixedCapacityVector<fvkmemory::resource_ptr<VulkanTexture>> mColors;
-    utils::FixedCapacityVector<fvkmemory::resource_ptr<VulkanSemaphore>> mFinishedDrawing;
    fvkmemory::resource_ptr<VulkanTexture> mDepth;
    VkExtent2D mExtent;
    uint32_t mLayerCount;
@@ -39,8 +39,6 @@ template ResourceType getTypeEnum<VulkanDescriptorSet>() noexcept;
 template ResourceType getTypeEnum<VulkanFence>() noexcept;
 template ResourceType getTypeEnum<VulkanBuffer>() noexcept;
 template ResourceType getTypeEnum<VulkanSync>() noexcept;
-template ResourceType getTypeEnum<VulkanMemoryMappedBuffer>() noexcept;
-template ResourceType getTypeEnum<VulkanSemaphore>() noexcept;

 template<typename D>
 ResourceType getTypeEnum() noexcept {
@@ -98,12 +96,6 @@ ResourceType getTypeEnum() noexcept {
    if constexpr (std::is_same_v<D, VulkanSync>) {
        return ResourceType::SYNC;
    }
-    if constexpr (std::is_same_v<D, VulkanMemoryMappedBuffer>) {
-        return ResourceType::MEMORY_MAPPED_BUFFER;
-    }
-    if constexpr (std::is_same_v<D, VulkanSemaphore>) {
-        return ResourceType::SEMAPHORE;
-    }
    return ResourceType::UNDEFINED_TYPE;
 }

@@ -145,10 +137,6 @@ std::string_view getTypeStr(ResourceType type) {
            return "VulkanBuffer";
        case ResourceType::SYNC:
            return "Sync";
-        case ResourceType::MEMORY_MAPPED_BUFFER:
-            return "VulkanMemoryMappedBuffer";
-        case ResourceType::SEMAPHORE:
-            return "Semaphore";
        case ResourceType::UNDEFINED_TYPE:
            return "";
    }
@@ -53,9 +53,7 @@ enum class ResourceType : uint8_t {
    STAGE_SEGMENT = 15,
    STAGE_IMAGE = 16,
    SYNC = 17,
-    MEMORY_MAPPED_BUFFER = 18,
-    SEMAPHORE = 19,
-    UNDEFINED_TYPE = 20,    // Must be the last enum because we use it for iterating over the enums.
+    UNDEFINED_TYPE = 18,    // Must be the last enum because we use it for iterating over the enums.
 };

 template<typename D>
@@ -117,12 +117,6 @@ void ResourceManager::destroyWithType(ResourceType type, HandleId id) {
        case ResourceType::SYNC:
            destruct<VulkanSync>(Handle<VulkanSync>(id));
            break;
-        case ResourceType::MEMORY_MAPPED_BUFFER:
-            destruct<VulkanMemoryMappedBuffer>(Handle<VulkanMemoryMappedBuffer>(id));
-            break;
-        case ResourceType::SEMAPHORE:
-            destruct<VulkanSemaphore>(Handle<VulkanSemaphore>(id));
-            break;
        case ResourceType::UNDEFINED_TYPE:
            break;
    }
@@ -201,9 +201,7 @@ ExtensionSet getInstanceExtensions(ExtensionSet const& externallyRequiredExts =
            fvkutils::enumerate(vkEnumerateInstanceExtensionProperties,
                    static_cast<char const*>(nullptr) /* pLayerName */);
    for (auto const& extension: availableExts) {
-        // The cast is to force the non-literal constructor of CString, which assumes
-        // null-terminated strings.
-        utils::CString name{ (char const*) extension.extensionName };
+        utils::CString name { extension.extensionName };

        // To workaround an Adreno bug where the extension name could be of 0 length.
        if (name.size() == 0) {
@@ -245,9 +243,7 @@ ExtensionSet getDeviceExtensions(VkPhysicalDevice device) {
            = fvkutils::enumerate(vkEnumerateDeviceExtensionProperties, device,
                    static_cast<const char*>(nullptr) /* pLayerName */);
    for (auto const& extension: extensions) {
-        // The cast is to force the non-literal constructor of CString, which assumes
-        // null-terminated strings.
-        utils::CString name { (char const*) extension.extensionName };
+        utils::CString name { extension.extensionName };

        // To workaround an Adreno bug where the extension name could be of 0 length.
        if (name.size() == 0) {
@@ -132,9 +132,8 @@ ShaderModel WebGPUDriver::getShaderModel() const noexcept {
 #endif
 }

-utils::FixedCapacityVector<ShaderLanguage> WebGPUDriver::getShaderLanguages(
-        ShaderLanguage /*preferredLanguage*/) const noexcept {
-    return { ShaderLanguage::WGSL };
+ShaderLanguage WebGPUDriver::getShaderLanguage() const noexcept {
+    return ShaderLanguage::WGSL;
 }

 // explicit instantiation of the Dispatcher
@@ -451,7 +450,7 @@ Handle<HwTexture> WebGPUDriver::createTextureExternalImagePlaneS() noexcept {
 // ------------------------------------------------------------------------------------------------

 void WebGPUDriver::createSwapChainR(Handle<HwSwapChain> sch, void* nativeWindow,
-        const uint64_t flags, utils::CString&& tag) {
+        const uint64_t flags, utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();

    // TODO: support MSAA swapchain
@@ -481,7 +480,7 @@ void WebGPUDriver::createSwapChainR(Handle<HwSwapChain> sch, void* nativeWindow,
 }

 void WebGPUDriver::createSwapChainHeadlessR(Handle<HwSwapChain> sch, uint32_t width,
-        uint32_t height, uint64_t flags, utils::CString&& tag) {
+        uint32_t height, uint64_t flags, utils::CString tag) {
     wgpu::Extent2D extent = { .width = width, .height = height };
     mSwapChain = constructHandle<WebGPUSwapChain>(sch, extent, mAdapter,
            mDevice, flags);
@@ -494,7 +493,7 @@ void WebGPUDriver::createSwapChainHeadlessR(Handle<HwSwapChain> sch, uint32_t wi

 void WebGPUDriver::createVertexBufferInfoR(Handle<HwVertexBufferInfo> vertexBufferInfoHandle,
        const uint8_t bufferCount, const uint8_t attributeCount, const AttributeArray attributes,
-        utils::CString&& tag) {
+        utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    constructHandle<WebGPUVertexBufferInfo>(vertexBufferInfoHandle, bufferCount, attributeCount,
            attributes, mDeviceLimits);
@@ -503,7 +502,7 @@ void WebGPUDriver::createVertexBufferInfoR(Handle<HwVertexBufferInfo> vertexBuff

 void WebGPUDriver::createVertexBufferR(Handle<HwVertexBuffer> vertexBufferHandle,
        const uint32_t vertexCount, Handle<HwVertexBufferInfo> vertexBufferInfoHandle,
-        utils::CString&& tag) {
+        utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    const auto vertexBufferInfo = handleCast<WebGPUVertexBufferInfo>(vertexBufferInfoHandle);
    constructHandle<WebGPUVertexBuffer>(vertexBufferHandle, vertexCount,
@@ -513,7 +512,7 @@ void WebGPUDriver::createVertexBufferR(Handle<HwVertexBuffer> vertexBufferHandle

 void WebGPUDriver::createIndexBufferR(Handle<HwIndexBuffer> indexBufferHandle,
        const ElementType elementType, const uint32_t indexCount, const BufferUsage usage,
-        utils::CString&& tag) {
+        utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    const auto elementSize = static_cast<uint8_t>(getElementTypeSize(elementType));
    constructHandle<WebGPUIndexBuffer>(indexBufferHandle, mDevice, elementSize, indexCount);
@@ -522,7 +521,7 @@ void WebGPUDriver::createIndexBufferR(Handle<HwIndexBuffer> indexBufferHandle,

 void WebGPUDriver::createBufferObjectR(Handle<HwBufferObject> bufferObjectHandle,
        const uint32_t byteCount, const BufferObjectBinding bindingType, const BufferUsage usage,
-        utils::CString&& tag) {
+        utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    constructHandle<WebGPUBufferObject>(bufferObjectHandle, mDevice, bindingType, byteCount);
    setDebugTag(bufferObjectHandle.getId(), std::move(tag));
@@ -531,7 +530,7 @@ void WebGPUDriver::createBufferObjectR(Handle<HwBufferObject> bufferObjectHandle
 void WebGPUDriver::createTextureR(Handle<HwTexture> textureHandle, const SamplerType target,
        const uint8_t levels, const TextureFormat format, const uint8_t samples,
        const uint32_t width, const uint32_t height, const uint32_t depth,
-        const TextureUsage usage, utils::CString&& tag) {
+        const TextureUsage usage, utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    constructHandle<WebGPUTexture>(textureHandle, target, levels, format, samples, width, height,
            depth, usage, mDevice);
@@ -540,7 +539,7 @@ void WebGPUDriver::createTextureR(Handle<HwTexture> textureHandle, const Sampler

 void WebGPUDriver::createTextureViewR(Handle<HwTexture> textureHandle,
        Handle<HwTexture> sourceTextureHandle, const uint8_t baseLevel, const uint8_t levelCount,
-        utils::CString&& tag) {
+        utils::CString tag) {
    auto source = handleCast<WebGPUTexture>(sourceTextureHandle);

    constructHandle<WebGPUTexture>(textureHandle, source, baseLevel, levelCount);
@@ -551,7 +550,7 @@ void WebGPUDriver::createTextureViewR(Handle<HwTexture> textureHandle,
 void WebGPUDriver::createTextureViewSwizzleR(Handle<HwTexture> textureHandle,
        Handle<HwTexture> sourceTextureHandle, const backend::TextureSwizzle r,
        const backend::TextureSwizzle g, const backend::TextureSwizzle b,
-        const backend::TextureSwizzle a, utils::CString&& tag) {
+        const backend::TextureSwizzle a, utils::CString tag) {

    if (!isTextureSwizzleSupported()) {
        FWGPU_LOGW << "WebGPUDriver::createTextureViewSwizzleR called while texture swizzling is "
@@ -578,7 +577,7 @@ void WebGPUDriver::createTextureViewSwizzleR(Handle<HwTexture> textureHandle,
 void WebGPUDriver::createTextureExternalImage2R(Handle<HwTexture> textureHandle,
        const backend::SamplerType target, const backend::TextureFormat format,
        const uint32_t width, const uint32_t height, const backend::TextureUsage usage,
-        Platform::ExternalImageHandleRef externalImage, utils::CString&& tag) {
+        Platform::ExternalImageHandleRef externalImage, utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    PANIC_POSTCONDITION("External WebGPU Texture is not supported");
 }
@@ -586,27 +585,27 @@ void WebGPUDriver::createTextureExternalImage2R(Handle<HwTexture> textureHandle,
 void WebGPUDriver::createTextureExternalImageR(Handle<HwTexture> textureHandle,
        const backend::SamplerType target, const backend::TextureFormat format,
        const uint32_t width, const uint32_t height, const backend::TextureUsage usage,
-        void* externalImage, utils::CString&& tag) {
+        void* externalImage, utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    PANIC_POSTCONDITION("External WebGPU Texture is not supported");
 }

 void WebGPUDriver::createTextureExternalImagePlaneR(Handle<HwTexture> textureHandle,
        const backend::TextureFormat format, const uint32_t width, const uint32_t height,
-        const backend::TextureUsage usage, void* image, const uint32_t plane, utils::CString&& tag) {
+        const backend::TextureUsage usage, void* image, const uint32_t plane, utils::CString tag) {
    PANIC_POSTCONDITION("External WebGPU Texture is not supported");
 }

 void WebGPUDriver::importTextureR(Handle<HwTexture> textureHandle, const intptr_t id,
        const SamplerType target, const uint8_t levels, const TextureFormat format,
        const uint8_t samples, const uint32_t width, const uint32_t height, const uint32_t depth,
-        const TextureUsage usage, utils::CString&& tag) {
+        const TextureUsage usage, utils::CString tag) {
    PANIC_POSTCONDITION("Import WebGPU Texture is not supported");
 }

 void WebGPUDriver::createRenderPrimitiveR(Handle<HwRenderPrimitive> renderPrimitiveHandle,
        Handle<HwVertexBuffer> vertexBufferHandle, Handle<HwIndexBuffer> indexBufferHandle,
-        const PrimitiveType primitiveType, utils::CString&& tag) {
+        const PrimitiveType primitiveType, utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    assert_invariant(mDevice);
    const auto renderPrimitive = constructHandle<WebGPURenderPrimitive>(renderPrimitiveHandle);
@@ -619,14 +618,14 @@ void WebGPUDriver::createRenderPrimitiveR(Handle<HwRenderPrimitive> renderPrimit
 }

 void WebGPUDriver::createProgramR(Handle<HwProgram> programHandle, Program&& program,
-        utils::CString&& tag) {
+        utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    constructHandle<WebGPUProgram>(programHandle, mDevice, program);
    setDebugTag(programHandle.getId(), std::move(tag));
 }

 void WebGPUDriver::createDefaultRenderTargetR(Handle<HwRenderTarget> renderTargetHandle,
-        utils::CString&& tag) {
+        utils::CString tag) {
    assert_invariant(!mDefaultRenderTarget);
    mDefaultRenderTarget = constructHandle<WebGPURenderTarget>(renderTargetHandle);
    assert_invariant(mDefaultRenderTarget);
@@ -639,7 +638,7 @@ void WebGPUDriver::createDefaultRenderTargetR(Handle<HwRenderTarget> renderTarge
 void WebGPUDriver::createRenderTargetR(Handle<HwRenderTarget> renderTargetHandle,
        const TargetBufferFlags targetFlags, const uint32_t width, const uint32_t height,
        const uint8_t samples, const uint8_t layerCount, const MRT color,
-        const TargetBufferInfo depth, const TargetBufferInfo stencil, utils::CString&& tag) {
+        const TargetBufferInfo depth, const TargetBufferInfo stencil, utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    constructHandle<WebGPURenderTarget>(
            renderTargetHandle, width, height, samples, layerCount, color, depth, stencil,
@@ -651,7 +650,7 @@ void WebGPUDriver::createRenderTargetR(Handle<HwRenderTarget> renderTargetHandle
    setDebugTag(renderTargetHandle.getId(), std::move(tag));
 }

-void WebGPUDriver::createFenceR(Handle<HwFence> fenceHandle, utils::CString&& tag) {
+void WebGPUDriver::createFenceR(Handle<HwFence> fenceHandle, utils::CString tag) {
    // The handle is constructed synchronously in createFenceS.
    const auto fence = handleCast<WebGPUFence>(fenceHandle);
    assert_invariant(mQueue);
@@ -659,24 +658,24 @@ void WebGPUDriver::createFenceR(Handle<HwFence> fenceHandle, utils::CString&& ta
    setDebugTag(fenceHandle.getId(), std::move(tag));
 }

-void WebGPUDriver::createSyncR(Handle<HwSync> syncHandle, utils::CString&& tag) {
+void WebGPUDriver::createSyncR(Handle<HwSync> syncHandle, utils::CString tag) {
    // TODO: Ensure sync is active, and then invoke and clear all pending
    // callbacks.
    setDebugTag(syncHandle.getId(), std::move(tag));
 }

-void WebGPUDriver::createTimerQueryR(Handle<HwTimerQuery> tqh, utils::CString&& tag) {}
+void WebGPUDriver::createTimerQueryR(Handle<HwTimerQuery> tqh, utils::CString tag) {}

 void WebGPUDriver::createDescriptorSetLayoutR(
        Handle<HwDescriptorSetLayout> descriptorSetLayoutHandle,
-        backend::DescriptorSetLayout&& info, utils::CString&& tag) {
+        backend::DescriptorSetLayout&& info, utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    constructHandle<WebGPUDescriptorSetLayout>(descriptorSetLayoutHandle, std::move(info), mDevice);
    setDebugTag(descriptorSetLayoutHandle.getId(), std::move(tag));
 }

 void WebGPUDriver::createDescriptorSetR(Handle<HwDescriptorSet> descriptorSetHandle,
-        Handle<HwDescriptorSetLayout> descriptorSetLayoutHandle, utils::CString&& tag) {
+        Handle<HwDescriptorSetLayout> descriptorSetLayoutHandle, utils::CString tag) {
    FWGPU_SYSTRACE_SCOPE();
    auto layout = handleCast<WebGPUDescriptorSetLayout>(descriptorSetLayoutHandle);
    constructHandle<WebGPUDescriptorSet>(descriptorSetHandle, layout->getLayout(),
@@ -733,14 +732,6 @@ FenceStatus WebGPUDriver::getFenceStatus(Handle<HwFence> fenceHandle) {
    return fence->getStatus();
 }

-FenceStatus WebGPUDriver::fenceWait(FenceHandle fenceHandle, uint64_t const timeout) {
-    const auto fence = handleCast<WebGPUFence>(fenceHandle);
-    if (!fence) {
-        return FenceStatus::ERROR;
-    }
-    return fence->wait(timeout);
-}
-
 void WebGPUDriver::destroySync(Handle<HwSync> syncHandle) {
    if (syncHandle) {
        destructHandle<WebGPUSync>(syncHandle);
@@ -791,7 +782,7 @@ bool WebGPUDriver::isFrameBufferFetchMultiSampleSupported() {
 }

 bool WebGPUDriver::isFrameTimeSupported() {
-    return false;
+    return true;
 }

 bool WebGPUDriver::isAutoDepthResolveSupported() {
@@ -2100,7 +2091,7 @@ void WebGPUDriver::bindDescriptorSet(Handle<HwDescriptorSet> descriptorSetHandle
        .offsets = std::move(offsets) };
 }

-void WebGPUDriver::setDebugTag(HandleBase::HandleId handleId, utils::CString&& tag) {
+void WebGPUDriver::setDebugTag(HandleBase::HandleId handleId, utils::CString tag) {
    //todo
 }

@@ -2216,25 +2207,4 @@ wgpu::AddressMode WebGPUDriver::fWrapModeToWAddressMode(const SamplerWrapMode& f
    return wgpu::AddressMode::Undefined;
 }

-MemoryMappedBufferHandle WebGPUDriver::mapBufferS() noexcept {
-    // TODO: MetalDriver::mapBufferS
-    return {};
-}
-
-void WebGPUDriver::mapBufferR(MemoryMappedBufferHandle mmbh,
-        BufferObjectHandle boh, size_t offset,
-        size_t size, MapBufferAccessFlags access, utils::CString&& tag) {
-    // TODO: MetalDriver::mapBufferR
-}
-
-void WebGPUDriver::unmapBuffer(MemoryMappedBufferHandle mmbh) {
-    // TODO: MetalDriver::unmapBuffer
-}
-
-void WebGPUDriver::copyToMemoryMappedBuffer(MemoryMappedBufferHandle mmbh, size_t offset,
-        BufferDescriptor&& data) {
-    // TODO: MetalDriver::copyToMemoryMappedBuffer
-}
-
-
 } // namespace filament::backend
@@ -33,7 +33,6 @@
 #include "private/backend/HandleAllocator.h"
 #include <backend/DriverEnums.h>

-#include <utils/FixedCapacityVector.h>
 #include <utils/compiler.h>

 #include "SpdMipmapGenerator/SpdMipmapGenerator.h"
@@ -66,11 +65,10 @@ public:
 private:
    WebGPUDriver(WebGPUPlatform& platform, const Platform::DriverConfig& driverConfig) noexcept;
    [[nodiscard]] ShaderModel getShaderModel() const noexcept final;
-    [[nodiscard]] utils::FixedCapacityVector<ShaderLanguage> getShaderLanguages(
-            ShaderLanguage preferredLanguage) const noexcept final;
+    [[nodiscard]] ShaderLanguage getShaderLanguage() const noexcept final;
    [[nodiscard]] wgpu::Sampler makeSampler(SamplerParams const& params);
    [[nodiscard]] static wgpu::AddressMode fWrapModeToWAddressMode(const filament::backend::SamplerWrapMode& fUsage);
-    void setDebugTag(HandleBase::HandleId handleId, utils::CString&& tag);
+    void setDebugTag(HandleBase::HandleId handleId, utils::CString tag);

    // The platform (e.g. OS) specific aspects of the WebGPU backend are strictly only
    // handled in the WebGPUPlatform.
@@ -19,72 +19,31 @@

 #include <backend/DriverEnums.h>

-#include <memory>
 #include <webgpu/webgpu_cpp.h>

-#include <condition_variable>
-#include <chrono>
-#include <cstdint>
-#include <mutex>
+#include <atomic>

 namespace filament::backend {

-WebGPUFence::~WebGPUFence() noexcept {
-    // if the fence was being waited on, make sure to return with an error
-    std::lock_guard const lock(state->lock);
-    state->status = FenceStatus::ERROR;
-    state->cond.notify_all();
-}
-
-FenceStatus WebGPUFence::getStatus() const {
-    std::lock_guard const lock(state->lock);
-    return state->status;
-}
-
-FenceStatus WebGPUFence::wait(uint64_t const timeout) {
-    // we have to take into account that the STL's wait_for() actually works with
-    // time_points relative to steady_clock::now() internally.
-    using namespace std::chrono;
-    auto const now = steady_clock::now();
-    steady_clock::time_point until = steady_clock::time_point::max();
-    if (now <= steady_clock::time_point::max() - nanoseconds(timeout)) {
-        until = now + nanoseconds(timeout);
-    }
-
-    std::unique_lock lock(state->lock);
-    state->cond.wait_until(lock, until,
-            [state = state] { return state->status != FenceStatus::TIMEOUT_EXPIRED; });
-    return state->status;
-}
+FenceStatus WebGPUFence::getStatus() { return mStatus.load(); }

 void WebGPUFence::addMarkerToQueueState(wgpu::Queue const& queue) {
    // The lambda function is called when the work is done. It updates the fence status based on the
    // result of the work.
-    // Because the callback holds a weak_ptr to the state of the HwFence object, it can be
-    // destroyed before the fence signals.
-    std::weak_ptr const weak = state;
    queue.OnSubmittedWorkDone(
-            wgpu::CallbackMode::AllowSpontaneous,
-            [weak](const wgpu::QueueWorkDoneStatus status, wgpu::StringView message) {
-                if (auto const state = weak.lock()) {
-                    std::unique_lock const lock(state->lock);
-                    if (state->status != FenceStatus::ERROR) {
-                        switch (status) {
-                            case wgpu::QueueWorkDoneStatus::Success:
-                                state->status = FenceStatus::CONDITION_SATISFIED;
-                                state->cond.notify_all();
-                                break;
-                            case wgpu::QueueWorkDoneStatus::CallbackCancelled:
-                            case wgpu::QueueWorkDoneStatus::Error:
-                                state->status = FenceStatus::ERROR;
-                                state->cond.notify_all();
-                                FWGPU_LOGW << "WebGPUFence: wgpu::QueueWorkDoneStatus::Error. " <<
-                                        message;
-                                break;
-                        }
-                    }
-                }
-            });
+        wgpu::CallbackMode::AllowSpontaneous,
+        [this](const wgpu::QueueWorkDoneStatus status, wgpu::StringView message) {
+            switch (status) {
+                case wgpu::QueueWorkDoneStatus::Success:
+                    mStatus.store(FenceStatus::CONDITION_SATISFIED);
+                    break;
+                case wgpu::QueueWorkDoneStatus::CallbackCancelled:
+                case wgpu::QueueWorkDoneStatus::Error:
+                    mStatus.store(FenceStatus::ERROR);
+                    FWGPU_LOGW << "WebGPUFence: wgpu::QueueWorkDoneStatus::Error. " << message;
+                    break;
+            }
+        });
 }

 } // namespace filament::backend
@@ -18,14 +18,9 @@
 #define TNT_FILAMENT_BACKEND_WEBGPUFENCE_H

 #include "DriverBase.h"
-
 #include <backend/DriverEnums.h>

-#include <utils/Mutex.h> // NOLINT(*-include-cleaner)
-#include <utils/Condition.h> // NOLINT(*-include-cleaner)
-
-#include <cstdint>
-#include <memory>
+#include <atomic>

 namespace wgpu {
 class Queue;
@@ -40,20 +35,15 @@ namespace filament::backend {
  */
 class WebGPUFence final : public HwFence {
 public:
-    ~WebGPUFence() noexcept;
-    [[nodiscard]] FenceStatus getStatus() const;
-    [[nodiscard]] FenceStatus wait(uint64_t timeout);
+    [[nodiscard]] FenceStatus getStatus();

    void addMarkerToQueueState(wgpu::Queue const&);

 private:
-    struct State {
-        utils::Mutex lock; // NOLINT(*-include-cleaner)
-        utils::Condition cond; // NOLINT(*-include-cleaner)
-        FenceStatus status{ FenceStatus::TIMEOUT_EXPIRED };
-    };
-    // we need a shared_ptr because the Fence could be destroyed while we're waiting
-    std::shared_ptr<State> state{ std::make_shared<State>() };
+    // The current status of the fence.
+    // This is atomic because it can be updated by a WebGPU callback thread and read from the main
+    // thread.
+    std::atomic<FenceStatus> mStatus{ FenceStatus::TIMEOUT_EXPIRED };
 };

 } // namespace filament::backend
@@ -39,12 +39,7 @@ Cleanup::~Cleanup() {
    for (const auto descriptorSetLayout : mDescriptorSetLayouts) {
        mDriverApi.destroyDescriptorSetLayout(descriptorSetLayout);
    }
-    for (const auto memoryMappedBuffer : mMemoryMappedBuffers) {
-        // destroy those before buffer objects
-        mDriverApi.unmapBuffer(memoryMappedBuffer);
-    }
    for (const auto bufferObject : mBufferObjects) {
-        // destroy those after memory mapped buffers
        mDriverApi.destroyBufferObject(bufferObject);
    }
    for (const auto program : mPrograms) {
@@ -56,18 +51,6 @@ Cleanup::~Cleanup() {
    for (const auto renderTarget : mRenderTargets) {
        mDriverApi.destroyRenderTarget(renderTarget);
    }
-    for (const auto renderPrimitive : mRenderPrimitives) {
-        mDriverApi.destroyRenderPrimitive(renderPrimitive);
-    }
-    for (const auto vertexBufferInfo : mVertexBufferInfos) {
-        mDriverApi.destroyVertexBufferInfo(vertexBufferInfo);
-    }
-    for (const auto indexBuffer : mIndexBuffers) {
-        mDriverApi.destroyIndexBuffer(indexBuffer);
-    }
-    for (const auto vertexBuffer : mVertexBuffers) {
-        mDriverApi.destroyVertexBuffer(vertexBuffer);
-    }

    for (const auto& callback : mCallbacks) {
        callback();
@@ -103,26 +86,6 @@ template <>
 void Cleanup::addInternal(filament::backend::RenderTargetHandle handle) {
    mRenderTargets.push_back(handle);
 }
-template <>
-void Cleanup::addInternal(filament::backend::MemoryMappedBufferHandle handle) {
-    mMemoryMappedBuffers.push_back(handle);
-}
-template <>
-void Cleanup::addInternal(filament::backend::RenderPrimitiveHandle handle) {
-    mRenderPrimitives.push_back(handle);
-}
-template <>
-void Cleanup::addInternal(filament::backend::VertexBufferInfoHandle handle) {
-    mVertexBufferInfos.push_back(handle);
-}
-template <>
-void Cleanup::addInternal(filament::backend::VertexBufferHandle handle) {
-    mVertexBuffers.push_back(handle);
-}
-template <>
-void Cleanup::addInternal(filament::backend::IndexBufferHandle handle) {
-    mIndexBuffers.push_back(handle);
-}

 void Cleanup::addPostCall(std::function<void()> callback){
    mCallbacks.emplace_back(std::move(callback));
@@ -68,11 +68,6 @@ private:
    std::vector<filament::backend::ProgramHandle> mPrograms;
    std::vector<filament::backend::TextureHandle> mTextures;
    std::vector<filament::backend::RenderTargetHandle> mRenderTargets;
-    std::vector<filament::backend::RenderPrimitiveHandle> mRenderPrimitives;
-    std::vector<filament::backend::VertexBufferInfoHandle> mVertexBufferInfos;
-    std::vector<filament::backend::VertexBufferHandle> mVertexBuffers;
-    std::vector<filament::backend::IndexBufferHandle> mIndexBuffers;
-    std::vector<filament::backend::MemoryMappedBufferHandle> mMemoryMappedBuffers;

    std::vector<std::function<void()>> mCallbacks;
 };
@@ -269,10 +269,6 @@ TEST_F(BlitTest, ColorResolve) {
    SKIP_IF(Backend::WEBGPU, "test cases fail in WebGPU, see b/424157731");
    auto& api = getDriverApi();

-    if (api.getFeatureLevel() < FeatureLevel::FEATURE_LEVEL_2) {
-        GTEST_SKIP() << "Skipping test because multi-sampled textures are not supported at Feature level < 2";
-    }
-
    constexpr int kSrcTexWidth = 256;
    constexpr int kSrcTexHeight = 256;
    constexpr int kDstTexWidth = 256;
@@ -25,6 +25,8 @@ using namespace filament::backend;
 namespace test {

 TEST_F(BackendTest, FrameScheduledCallback) {
+    SKIP_IF(Backend::OPENGL, "Frame callbacks are unsupported in OpenGL");
+    SKIP_IF(Backend::VULKAN, "Frame callbacks are unsupported in Vulkan, see b/417254479");
    SKIP_IF(Backend::WEBGPU, "Frame callbacks are unsupported in WebGPU");

    auto& api = getDriverApi();
@@ -66,18 +68,7 @@ TEST_F(BackendTest, FrameScheduledCallback) {
        callbackCountB++;
    }, 0);

-    // Render another frame.
-    api.makeCurrent(swapChain, swapChain);
-    api.beginFrame(0, 0, 0);
-    api.beginRenderPass(renderTarget, {});
-    api.endRenderPass(0);
-    api.commit(swapChain);
-    api.endFrame(0);
-
-    // Now, unset the callback
-    api.setFrameScheduledCallback(swapChain, nullptr, {}, 0);
-
-    // Render a final frame. This time no callback should be called.
+    // Render one final frame.
    api.makeCurrent(swapChain, swapChain);
    api.beginFrame(0, 0, 0);
    api.beginRenderPass(renderTarget, {});
@@ -392,6 +392,10 @@ TEST_F(LoadImageTest, UpdateImage2D) {
 }

 TEST_F(LoadImageTest, UpdateImageSRGB) {
+    FAIL_IF(SkipEnvironment(OperatingSystem::APPLE, Backend::VULKAN),
+            "Crashing when reading pixels without a redundant call to makeCurrent right before the"
+            "render pass. b/422798473");
+
    auto& api = getDriverApi();
    Cleanup cleanup(api);
    api.startCapture();
@@ -476,6 +480,10 @@ TEST_F(LoadImageTest, UpdateImageSRGB) {
 }

 TEST_F(LoadImageTest, UpdateImageMipLevel) {
+    FAIL_IF(SkipEnvironment(OperatingSystem::APPLE, Backend::VULKAN),
+            "Crashing when reading pixels without a redundant call to makeCurrent right before the"
+            "render pass. b/422798473");
+
    auto& api = getDriverApi();
    Cleanup cleanup(api);
    api.startCapture();
@@ -511,6 +519,8 @@ TEST_F(LoadImageTest, UpdateImageMipLevel) {
    PixelBufferDescriptor descriptor = checkerboardPixelBuffer(pixelFormat, pixelType, kTexSize);
    api.update3DImage(texture, /* level*/ 1, 0, 0, 0, kTexSize, kTexSize, 1, std::move(descriptor));

+    api.beginFrame(0, 0, 0);
+
    // Update samplers.
    DescriptorSetHandle descriptorSet = shader.createDescriptorSet(api);
    api.updateDescriptorSetTexture(descriptorSet, 0, texture, {
@@ -534,12 +544,13 @@ TEST_F(LoadImageTest, UpdateImageMipLevel) {
        api.bindRenderPrimitive(mTriangle.getRenderPrimitive());
        api.draw2(0, 3, 1);
        api.endRenderPass();
-
-        EXPECT_IMAGE(defaultRenderTarget,
-                ScreenshotParams(kTexSize, kTexSize, "UpdateImageMipLevel", 1875922935));
    }

+    EXPECT_IMAGE(defaultRenderTarget,
+            ScreenshotParams(kTexSize, kTexSize, "UpdateImageMipLevel", 1875922935));
+
    api.commit(swapChain);
+    api.endFrame(0);

    api.stopCapture();
 }
@@ -1,388 +0,0 @@
-/*
- * Copyright (C) 2025 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "BackendTest.h"
-
-#include "ImageExpectations.h"
-#include "Lifetimes.h"
-#include "Shader.h"
-#include "SharedShaders.h"
-#include "SharedShadersConstants.h"
-#include "Skip.h"
-
-#include <backend/BufferDescriptor.h>
-#include <backend/DriverEnums.h>
-#include <backend/Handle.h>
-#include <backend/PipelineState.h>
-
-#include <math/vec2.h>
-#include <math/vec4.h>
-
-#include <gtest/gtest.h>
-
-#include <array>
-#include <cstdint>
-#include <cstddef>
-#include <new>
-#include <tuple>
-#include <utility>
-
-#include <stdlib.h>
-#include <string.h>
-
-namespace test {
-
-using namespace filament;
-using namespace filament::backend;
-
-class MemoryMappedTest : public BackendTest {
-protected:
-    RenderTargetHandle makeRenderTarget(Cleanup& cleanup) {
-        auto& api = getDriverApi();
-        auto colorTexture = cleanup.add(
-                api.createTexture(SamplerType::SAMPLER_2D, 1, TextureFormat::RGBA8, 1,
-                        screenWidth(), screenHeight(), 1,
-                        TextureUsage::COLOR_ATTACHMENT | TextureUsage::SAMPLEABLE));
-        auto renderTarget = cleanup.add(api.createRenderTarget(TargetBufferFlags::COLOR0,
-                screenWidth(), screenHeight(), 1, 1, { { colorTexture } }, {}, {}));
-        return renderTarget;
-    }
-
-    std::tuple<VertexBufferInfoHandle, VertexBufferHandle, IndexBufferHandle>
-    setupGeometryBuffer(Cleanup& cleanup,
-            uint32_t const count, uint8_t const stride, uint32_t const baseVertex,
-            BufferObjectHandle buffer) {
-        auto& api = getDriverApi();
-        AttributeArray attributes = {};
-        attributes[0] = { .offset = 0, .stride = stride, .buffer = 0, .type = ElementType::FLOAT2 };
-        auto vbih = cleanup.add(api.createVertexBufferInfo(1, 1, attributes));
-        // The vertex buffer must be large enough to hold the "garbage" vertices created by the offset.
-        auto vbh = cleanup.add(api.createVertexBuffer(count + baseVertex, vbih));
-        api.setVertexBufferObject(vbh, 0, buffer);
-
-        auto* const indices = new(std::nothrow)uint16_t[count];
-        for (size_t i = 0; i < count; i++) {
-            indices[i] = i + baseVertex;
-        }
-
-        auto ibh = cleanup.add(
-                api.createIndexBuffer(ElementType::USHORT, count, BufferUsage::STATIC));
-
-        api.updateIndexBuffer(ibh, {
-                indices, count * sizeof(uint16_t),
-                [](void* b, size_t, void*) {
-                    delete [] static_cast<uint16_t*>(b);
-                }, indices }, 0);
-
-        return { vbih, vbh, ibh };
-    }
-
-    Shader getSimpleShader(Cleanup& cleanup, math::float4 const& color) {
-        auto& api = getDriverApi();
-        Shader const shader = SharedShaders::makeShader(getDriverApi(), cleanup, ShaderRequest{
-            .mVertexType = VertexShaderType::Simple,
-            .mFragmentType = FragmentShaderType::SolidColored,
-            .mUniformType = ShaderUniformType::Simple
-        });
-
-        auto const ubuffer = cleanup.add(api.createBufferObject(sizeof(SimpleMaterialParams),
-                BufferObjectBinding::UNIFORM, BufferUsage::DYNAMIC_BIT));
-        shader.bindUniform<SimpleMaterialParams>(api, ubuffer);
-        shader.uploadUniform(api, ubuffer, SimpleMaterialParams{ .color = color });
-        return shader;
-    }
-
-    void copyData(const void* data, size_t const size, size_t const offset,
-            MemoryMappedBufferHandle const& mmb, int& callbacksExecuted) {
-        auto& api = getDriverApi();
-        void* p = malloc(size);
-        memcpy(p, data, size);
-        api.copyToMemoryMappedBuffer(mmb, offset, {
-            p, size, [](void* buffer, size_t, void* user) {
-                free(buffer);
-                (*static_cast<int*>(user))++;
-            }, &callbacksExecuted
-        });
-    }
-
-    void render(uint32_t count,
-            int64_t const frame,
-            SwapChainHandle swapChain,
-            RenderTargetHandle renderTarget,
-            RenderPrimitiveHandle renderPrimitive, PipelineState const& state) {
-        auto& api = getDriverApi();
-        RenderPassParams params = getClearColorRenderPass({0,0,0,1});
-        params.viewport = getFullViewport();
-
-        api.beginFrame(frame, 0, 0);
-        api.beginRenderPass(renderTarget, params);
-        api.bindPipeline(state);
-        api.bindRenderPrimitive(renderPrimitive);
-        api.draw2(0, count, 1);
-        api.endRenderPass();
-
-        api.commit(swapChain);
-        api.endFrame(0);
-        flushAndWait();
-    }
-
-    void runOffsetRenderTest(size_t const mapOffset,
-            size_t const copyOffset,
-            const math::float4& color,
-            const char* screenshotName) {
-
-        SKIP_IF(Backend::WEBGPU, "HwMemoryMappedBuffer APIs not yet implemented");
-
-        auto& api = getDriverApi();
-        Cleanup cleanup(api);
-
-        auto const swapChain = cleanup.add(createSwapChain());
-        api.makeCurrent(swapChain, swapChain);
-
-        auto const renderTarget = makeRenderTarget(cleanup);
-
-        constexpr std::array<math::float2, 3> vertices = {{
-            {-0.25f, -0.25f},
-            { 0.25f, -0.25f},
-            {-0.25f,  0.25f},
-        }};
-        constexpr size_t vertexDataSize = vertices.size() * sizeof(math::float2);
-        constexpr size_t stride = sizeof(math::float2);
-
-        // The total offset is the sum of the map and copy offsets.
-        const size_t totalOffset = mapOffset + copyOffset;
-
-        // Calculate how many vertices we need to skip to account for the total offset.
-        const uint32_t baseVertex = totalOffset / stride;
-
-        // Create a buffer large enough to hold the offset and the vertex data.
-        auto const bufferObject = cleanup.add(api.createBufferObject(vertexDataSize + totalOffset,
-                BufferObjectBinding::VERTEX, BufferUsage::SHARED_WRITE_BIT));
-
-        int callbackExecuted = 0;
-        // Map the buffer with a specific offset.
-        MemoryMappedBufferHandle const memoryMappedBuffer =
-                api.mapBuffer(bufferObject, mapOffset, vertexDataSize + copyOffset,
-                MapBufferAccessFlags::WRITE_BIT, utils::CString{ screenshotName });
-
-        copyData(vertices.data(), vertexDataSize, copyOffset, memoryMappedBuffer, callbackExecuted);
-
-        api.unmapBuffer(memoryMappedBuffer);
-
-        flushAndWait();
-        EXPECT_EQ(callbackExecuted, 1);
-
-        Shader const shader = getSimpleShader(cleanup, color);
-
-        auto [vbih, vbh, ibh] = setupGeometryBuffer(cleanup, 3, stride, baseVertex, bufferObject);
-
-        auto const renderPrimitive = cleanup.add(api.createRenderPrimitive(vbh, ibh, PrimitiveType::TRIANGLES));
-
-        PipelineState state = getColorWritePipelineState();
-        shader.addProgramToPipelineState(state);
-        state.rasterState.culling = CullingMode::NONE;
-        state.primitiveType = PrimitiveType::TRIANGLES;
-        state.vertexBufferInfo = vbih;
-
-        render(3, 0, swapChain, renderTarget, renderPrimitive, state);
-
-        EXPECT_IMAGE(renderTarget, ScreenshotParams(screenWidth(), screenHeight(), screenshotName, 0));
-    }
-};
-
-TEST_F(MemoryMappedTest, MapCopyUnmap) {
-    SKIP_IF(Backend::WEBGPU, "HwMemoryMappedBuffer APIs not yet implemented");
-
-    auto& api = getDriverApi();
-    Cleanup cleanup(api);
-
-    // Create a buffer object.
-    BufferObjectHandle const bufferObject = cleanup.add(api.createBufferObject(1024,
-            BufferObjectBinding::VERTEX, BufferUsage::DYNAMIC_BIT | BufferUsage::SHARED_WRITE_BIT));
-
-    // Map the buffer.
-    MemoryMappedBufferHandle const memoryMappedBuffer = api.mapBuffer(bufferObject, 0, 1024,
-            MapBufferAccessFlags::WRITE_BIT, "MemoryMappedBuffer");
-
-    if (memoryMappedBuffer) {
-        // Create some data to copy.
-        constexpr size_t dataSize = 256;
-        auto* const data = new uint8_t[dataSize];
-        for (size_t i = 0; i < dataSize; ++i) {
-            data[i] = uint8_t(i);
-        }
-
-        // Copy the data into the mapped buffer.
-        BufferDescriptor bufferDescriptor(data, dataSize, [](void* buffer, size_t, void*) {
-            delete[] static_cast<uint8_t*>(buffer);
-        });
-        api.copyToMemoryMappedBuffer(memoryMappedBuffer, 0, std::move(bufferDescriptor));
-
-        // Unmap the buffer.
-        api.unmapBuffer(memoryMappedBuffer);
-    }
-}
-
-TEST_F(MemoryMappedTest, WriteAndRender) {
-    runOffsetRenderTest(0, 0, {1, 0, 0, 1}, "WriteAndRender");
-}
-
-TEST_F(MemoryMappedTest, MapWithOffset) {
-    runOffsetRenderTest(16, 0, {0, 1, 0, 1}, "MapWithOffset");
-}
-
-TEST_F(MemoryMappedTest, CopyWithOffset) {
-    runOffsetRenderTest(0, 16, {0, 0, 1, 1}, "CopyWithOffset");
-}
-
-TEST_F(MemoryMappedTest, MapAndCopyWithOffsets) {
-    runOffsetRenderTest(16, 32, {1, 0, 1, 1}, "MapAndCopyWithOffsets");
-}
-
-TEST_F(MemoryMappedTest, MultipleCopies) {
-    SKIP_IF(Backend::WEBGPU, "HwMemoryMappedBuffer APIs not yet implemented");
-
-    auto& api = getDriverApi();
-    Cleanup cleanup(api);
-
-    auto const swapChain = cleanup.add(createSwapChain());
-    api.makeCurrent(swapChain, swapChain);
-
-    auto const renderTarget = makeRenderTarget(cleanup);
-
-    constexpr std::array<math::float2, 3> triangle1 = {{{-0.5f, 0.5f}, {-0.8f, 0.2f}, {-0.2f, 0.2f}}};
-    constexpr std::array<math::float2, 3> triangle2 = {{{0.5f, 0.5f}, {0.2f, 0.2f}, {0.8f, 0.2f}}};
-    constexpr std::array<math::float2, 3> triangle3 = {{{-0.5f, -0.5f}, {-0.8f, -0.8f}, {-0.2f, -0.8f}}};
-    constexpr size_t singleTriangleSize = triangle1.size() * sizeof(math::float2);
-    constexpr size_t totalDataSize = singleTriangleSize * 3;
-
-    auto const bufferObject = cleanup.add(api.createBufferObject(totalDataSize,
-            BufferObjectBinding::VERTEX, BufferUsage::SHARED_WRITE_BIT));
-
-    int callbacksExecuted = 0;
-    MemoryMappedBufferHandle const memoryMappedBuffer = api.mapBuffer(bufferObject, 0, totalDataSize,
-            MapBufferAccessFlags::WRITE_BIT, "MultipleCopies");
-
-    copyData(triangle1.data(), singleTriangleSize, 0,
-            memoryMappedBuffer, callbacksExecuted);
-    copyData(triangle2.data(), singleTriangleSize, singleTriangleSize,
-            memoryMappedBuffer, callbacksExecuted);
-    copyData(triangle3.data(), singleTriangleSize, singleTriangleSize * 2,
-            memoryMappedBuffer, callbacksExecuted);
-
-    api.unmapBuffer(memoryMappedBuffer);
-
-    flushAndWait();
-    EXPECT_EQ(callbacksExecuted, 3);
-
-    Shader const shader = getSimpleShader(cleanup, { 1, 1, 0, 1 });
-
-    auto [vbih, vbh, ibh] = setupGeometryBuffer(cleanup, 9, sizeof(math::float2), 0, bufferObject);
-
-    auto const renderPrimitive = cleanup.add(api.createRenderPrimitive(vbh, ibh, PrimitiveType::TRIANGLES));
-
-    PipelineState state = getColorWritePipelineState();
-    shader.addProgramToPipelineState(state);
-    state.rasterState.culling = CullingMode::NONE;
-    state.primitiveType = PrimitiveType::TRIANGLES;
-    state.vertexBufferInfo = vbih;
-
-    render(9, 0, swapChain, renderTarget, renderPrimitive, state);
-
-    EXPECT_IMAGE(renderTarget, ScreenshotParams(screenWidth(), screenHeight(), "MultipleCopies", 0));
-}
-
-TEST_F(MemoryMappedTest, UpdatePartial) {
-    SKIP_IF(Backend::WEBGPU, "HwMemoryMappedBuffer APIs not yet implemented");
-
-    auto& api = getDriverApi();
-    Cleanup cleanup(api);
-
-    auto swapChain = cleanup.add(createSwapChain());
-    api.makeCurrent(swapChain, swapChain);
-
-    auto renderTarget = makeRenderTarget(cleanup);
-
-    constexpr std::array<math::float2, 3> triangle1 = {{{-0.5f, 0.5f}, {-0.8f, 0.2f}, {-0.2f, 0.2f}}};
-    constexpr std::array<math::float2, 3> triangle2 = {{{0.5f, 0.5f}, {0.2f, 0.2f}, {0.8f, 0.2f}}};
-    constexpr std::array<math::float2, 3> triangle3 = {{{-0.5f, -0.5f}, {-0.8f, -0.8f}, {-0.2f, -0.8f}}};
-    constexpr size_t singleTriangleSize = triangle1.size() * sizeof(math::float2);
-    constexpr size_t totalDataSize = singleTriangleSize * 3;
-
-    auto bufferObject = cleanup.add(api.createBufferObject(totalDataSize,
-            BufferObjectBinding::VERTEX, BufferUsage::SHARED_WRITE_BIT));
-
-    int callbacksExecuted = 0;
-
-    // Initial data upload
-    {
-        MemoryMappedBufferHandle const memoryMappedBuffer = api.mapBuffer(bufferObject, 0, totalDataSize,
-                MapBufferAccessFlags::WRITE_BIT, "UpdatePartial_initial");
-
-        copyData(triangle1.data(), singleTriangleSize, 0,
-                memoryMappedBuffer, callbacksExecuted);
-        copyData(triangle2.data(), singleTriangleSize, singleTriangleSize,
-                memoryMappedBuffer, callbacksExecuted);
-        copyData(triangle3.data(), singleTriangleSize, singleTriangleSize * 2,
-                memoryMappedBuffer, callbacksExecuted);
-        api.unmapBuffer(memoryMappedBuffer);
-
-        flushAndWait();
-        EXPECT_EQ(callbacksExecuted, 3);
-    }
-
-
-    Shader const shader = getSimpleShader(cleanup, { 1, 1, 0, 1 });
-
-    auto [vbih, vbh, ibh] = setupGeometryBuffer(cleanup, 9, sizeof(math::float2), 0, bufferObject);
-
-    auto renderPrimitive = cleanup.add(api.createRenderPrimitive(vbh, ibh, PrimitiveType::TRIANGLES));
-
-    PipelineState state = getColorWritePipelineState();
-    shader.addProgramToPipelineState(state);
-    state.rasterState.culling = CullingMode::NONE;
-    state.primitiveType = PrimitiveType::TRIANGLES;
-    state.vertexBufferInfo = vbih;
-
-    render(9, 0, swapChain, renderTarget, renderPrimitive, state);
-
-    EXPECT_IMAGE(renderTarget, ScreenshotParams(screenWidth(), screenHeight(), "UpdatePartial_before", 0));
-
-    // Now, update the middle triangle
-    constexpr std::array<math::float2, 3> triangle2_updated = {{{0.5f, -0.5f}, {0.2f, -0.8f}, {0.8f, -0.8f}}};
-    callbacksExecuted = 0;
-    {
-        MemoryMappedBufferHandle const memoryMappedBuffer =
-                api.mapBuffer(bufferObject, singleTriangleSize, singleTriangleSize,
-                MapBufferAccessFlags::WRITE_BIT, "UpdatePartial_update");
-
-        copyData(triangle2_updated.data(), singleTriangleSize, 0, memoryMappedBuffer, callbacksExecuted);
-        api.unmapBuffer(memoryMappedBuffer);
-
-        flushAndWait();
-        EXPECT_EQ(callbacksExecuted, 1);
-    }
-
-    // need this because render() above calls commit()
-    api.makeCurrent(swapChain, swapChain);
-
-    // Second render, after update
-    render(9, 1, swapChain, renderTarget, renderPrimitive, state);
-
-    EXPECT_IMAGE(renderTarget, ScreenshotParams(screenWidth(), screenHeight(), "UpdatePartial_after", 0));
-}
-
-} // namespace test
--- a/Show More
+++ b/Show More