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See >>>> virtio_gpu_fence_event_create() for an example of adding new event >>>> types. Although maybe you want it to be an event which is not device >>>> specific. This isn't so much of a debugging use-case as simply >>>> notification. >>> Hi, >>> >>> for this particular use case, are we now talking about the display >>> device (KMS) crashing or the rendering device (OpenGL/Vulkan) crashing? >>> >>> If the former, I wasn't aware that display device crashes are a thing. >>> How should a userspace display server react to those? >>> >>> If the latter, don't we have EGL extensions or Vulkan API already to >>> deliver that? >>> >>> The above would be about device crashes that directly affect the >>> display server. Is that the use case in mind here, or is it instead >>> about notifying the display server that some application has caused a >>> driver/hardware crash? If the latter, how should a display server react >>> to that? Disconnect the application? >>> >>> Shashank, what is the actual use case you are developing this for? >>> >>> I've read all the emails here so far, and I don't recall seeing it >>> explained. >>> >> The idea is that a support daemon or compositor would listen for GPU >> reset notifications and do something useful with them (kill the guilty >> app, restart the desktop environment, etc.). Today when the GPU >> resets, most applications just continue assuming nothing is wrong, >> meanwhile the GPU has stopped accepting work until the apps re-init >> their context so all of their command submissions just get rejected. > Just one thing comes to mind reading this, racy PID reuse. > > process 1234 does something bad to GPU. > process 1234 dies in parallel to sysfs notification being sent. > other process 1234 reuses the pid > new process 1234 gets destroyed by receiver of sysfs notification. That's a well known problem inherit to the uses of PIDs. IIRC because of this the kernel only reuses PIDs when /proc/sys/kernel/pid_max is reached and then wraps around. Regards, Christian. > > Dave. 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See >>>> virtio_gpu_fence_event_create() for an example of adding new event >>>> types. Although maybe you want it to be an event which is not device >>>> specific. This isn't so much of a debugging use-case as simply >>>> notification. >>> Hi, >>> >>> for this particular use case, are we now talking about the display >>> device (KMS) crashing or the rendering device (OpenGL/Vulkan) crashing? >>> >>> If the former, I wasn't aware that display device crashes are a thing. >>> How should a userspace display server react to those? >>> >>> If the latter, don't we have EGL extensions or Vulkan API already to >>> deliver that? >>> >>> The above would be about device crashes that directly affect the >>> display server. Is that the use case in mind here, or is it instead >>> about notifying the display server that some application has caused a >>> driver/hardware crash? If the latter, how should a display server react >>> to that? Disconnect the application? >>> >>> Shashank, what is the actual use case you are developing this for? >>> >>> I've read all the emails here so far, and I don't recall seeing it >>> explained. >>> >> The idea is that a support daemon or compositor would listen for GPU >> reset notifications and do something useful with them (kill the guilty >> app, restart the desktop environment, etc.). Today when the GPU >> resets, most applications just continue assuming nothing is wrong, >> meanwhile the GPU has stopped accepting work until the apps re-init >> their context so all of their command submissions just get rejected. > Just one thing comes to mind reading this, racy PID reuse. > > process 1234 does something bad to GPU. > process 1234 dies in parallel to sysfs notification being sent. > other process 1234 reuses the pid > new process 1234 gets destroyed by receiver of sysfs notification. That's a well known problem inherit to the uses of PIDs. IIRC because of this the kernel only reuses PIDs when /proc/sys/kernel/pid_max is reached and then wraps around. Regards, Christian. > > Dave.