Hi Am 24.01.23 um 15:12 schrieb Christian König:
Hi Thomas,we ran into a problem with the general fbcon/fbdev implementation and though that you might have some idea.What happens is the following: 1. We load amdgpu and get our normal fbcon. 2. fbcon allocates a dump BO as backing store for the console.3. GDM/X/Applications start, new framebuffers are created BOs imported, exported etc... 4. Somehow X or GDM iterated over all the framebuffer objects the kernels knows about and export them as DMA-buf. 5. Application/X/GDM are stopped, handles closed, framebuffers released etc...6. We unbind vtcon.At this point the amdgpu module usually has a reference count of 0 and can be unloaded, but since GDM/X/Whoever iterated over all the known framebuffers and exported them as DMA-buf (for whatever reason idk) we now still have an exported DMA-buf and with it a reference to the module.Any idea how we could prevent that?
No real clue, sorry.But does it change if you use a shadow buffer on top of the amdgpu BO? Set prefer_shadow_fbdev = 1. [1] I once tried to run generic fbdev without prefer_shadow_fbdev and it never worked. I suspected that some reference counting got wrong, but could never pin it down. Maybe your issue is similar.
That said, generic fbdev is not so super-optimal for TTM-based drivers. I'm working on improving that, but it's not there yet.
Best regards Thomas[1] https://elixir.bootlin.com/linux/v6.0/source/include/drm/drm_mode_config.h#L890
Thanks, Christian.
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
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