We’re seeing a crash the second time we run our app. This is the error in the log:
May 30 10:34:06 Ryan-Lancasters-iPhone Submerged <Warning>: Fatal error: [File:/Users/UG_iMac/Perforce/Submerged_Moblie/Engine/Source/Runtime/Apple/MetalRHI/Private/MetalCommandList.cpp] [Line: 51] Command Buffer Frame2 Failure! Error Domain: MTLCommandBufferErrorDomain Code: 2 Description Caused GPU Hang Error (IOAF code 3) Unknown Unknown
Googling “IOAF code 3” I found this page: IOAF code 3 when using threadgroup… | Apple Developer Forums
It basically says that the hang/crash is caused by the threadgroup_barrier function not being encountered by all threads in the thread group.
I found the code in the engine that puts this function into the Metal shader and there was this comment above the code (MetalBackend.cpp line 1901):
//@todo-rco: Fix this properly
Any chance this has been “fixed properly” yet?