[PATCH v4 00/14] RFC Support hot device unplug in amdgpu

[Andrey Grodzovsky]

Looked a bit into it, I want to export sync_object to FD and import  from that FD
such that I will wait on the imported sync object handle from one thread while
signaling the exported sync object handle from another (post device unplug) ?

My problem is how to create a sync object with a non signaled 'fake' fence ?
I only see API that creates it with already signaled fence (or none) - 
https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/drm_syncobj.c#L56

P.S I expect the kernel to crash since unlike with dma_bufs we don't hold
drm device reference here on export.

Andrey

On 2/9/21 4:50 AM, Daniel Vetter wrote:
> Yeah in the end we'd need 2 hw devices for testing full fence
> functionality. A useful intermediate step would be to just export the
> fence (either as sync_file, which I think amdgpu doesn't support because
> no android egl support in mesa) or drm_syncobj (which you can do as
> standalone fd too iirc), and then just using the fence a bit from
> userspace (like wait on it or get its status) after the device is
> unplugged.