kc3-lang/angle/extensions/EGL_ANGLE_metal_commands_scheduled_sync.txt

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• Hash : 774bca93
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  Date : 2025-10-08T18:41:13
  

  [metal] Add commands scheduled sync object
  
  We need a thread-safe way to wait for ANGLE Metal command buffers to be
  scheduled for IOSurface synchronization with DrDC + Graphite on Mac.
  The existing eglWaitUntilWorkScheduledANGLE API isn't thread-safe as it
  reaches into ContextMtl innards to flush the command buffer.
  
  This CL adds the EGL_ANGLE_metal_commands_scheduled_sync extension which
  introduces a EGL_SYNC_METAL_COMMANDS_SCHEDULED_ANGLE sync object type.
  This sync object is signaled when pending Metal commands are scheduled
  to run on the GPU (MTLCommandBufferStatusScheduled). These sync objects
  are thread-safe - eglClientWaitSync() can be called on any thread even
  without a current context which is needed for DrDC + Graphite on Mac.
  
  Bug: chromium:444702048
  Change-Id: Ia13b352385a6fefaa026526ef74f6e596a6a6964
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/7027996
  Auto-Submit: Sunny Sachanandani <sunnyps@chromium.org>
  Reviewed-by: Quyen Le <lehoangquyen@chromium.org>
  Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
  Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
  

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• extensions/EGL_ANGLE_metal_commands_scheduled_sync.txt

• Name
  
      ANGLE_metal_commands_scheduled_sync
  
  Name Strings
  
      EGL_ANGLE_metal_commands_scheduled_sync
  
  Contributors
  
      Sunny Sachanandani, Google
  
  Contacts
  
      Sunny Sachanandani, Google (sunnyps `at` google.com)
  
  Status
  
      Draft
  
  Version
  
      Version 1, 2025-10-09
  
  Number
  
      EGL Extensions XXX
  
  Extension Type
  
      EGL display extension
  
  Dependencies
  
      This extension is written against the wording of the EGL 1.5
      Specification.
  
  Overview
  
      This extension enables the creation of EGL fence sync objects that are
      signaled when any pending Metal commands are scheduled on the GPU. The EGL
      fence sync objects have nearly identical semantics to those sync objects
      defined by the EGL 1.5 Specification, except where noted.
  
      Creating the sync object flushes any pending work. These sync objects are
      thread-safe and can be waited on from any thread with eglClientWaitSync
      without a current context. Note that eglWaitSync is a no-op for these
      sync objects since they only track CPU side scheduling of GPU commands. In
      particular, specifying EGL_SYNC_FLUSH_COMMANDS_BIT has no effect either
      since pending work is always flushed on creation of the sync object.
  
  New Types
  
      None.
  
  New Procedures and Functions
  
      None.
  
  New Tokens
  
      Accepted by the <type> parameter of eglCreateSync, and returned
      in <value> when eglGetSyncAttrib is called with <attribute>
      EGL_SYNC_TYPE:
  
      EGL_SYNC_METAL_COMMANDS_SCHEDULED_ANGLE             0x34E0
  
  Additions to the EGL Specification
  
      Add the following after the first paragraph of Section 3.8.1.1 (Creating
      Fence Sync Objects),
  
      "If <type> is EGL_SYNC_METAL_COMMANDS_SCHEDULED_ANGLE, an EGL commands
      scheduled sync object is created. No attributes may be specified in this
      case.
  
      The default values for the EGL commands scheduled sync object attributes
      are as follows:
  
        Attribute Name                     Initial Attribute Value(s)
        --------------                     --------------------------
        EGL_SYNC_TYPE                      EGL_SYNC_METAL_COMMANDS_SCHEDULED_ANGLE
        EGL_SYNC_STATUS                    EGL_UNSIGNALED
        EGL_SYNC_CONDITION                 EGL_SYNC_PRIOR_COMMANDS_COMPLETE
  
      Modify the list of eglCreateSync errors in Section 3.8.1.2 (Creating OpenCL
      Event Sync Objects)
  
      "Errors
       ------
      ..."
  
      Modify the second paragraph of Section 3.8.1.1 (Creating Fence Sync Objects),
  
      "When a fence sync object is created or when an EGL commands scheduled sync
      object is created, eglCreateSync also inserts a fence command into the
      command stream of the bound client API’s current context (i.e., the
      context returned by eglGetCurrentContext), and associates it with the newly
      created sync object."
  
  Issues
  
      None.
  
  Revision History
  
      Version 1, 2025-10-09
        - Initial draft
  

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