Messages in this thread | | | Date | Tue, 16 Aug 2022 14:03:49 +0200 | Subject | Re: [PATCH v8 2/2] drm/gem: Don't map imported GEMs | From | Christian König <> |
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Am 16.08.22 um 13:44 schrieb Dmitry Osipenko: > [SNIP] >> The other complication I noticed is that we don't seem to keep around >> the fd after importing to a GEM handle. And I could imagine that >> doing so could cause issues with too many fd's. So I guess the best >> thing is to keep the status quo and let drivers that cannot mmap >> imported buffers just fail mmap? > That actually should be all the drivers excluding those that use > DRM-SHMEM because only DRM-SHMEM uses dma_buf_mmap(), that's why it > works for Panfrost. I'm pretty sure mmaping of imported GEMs doesn't > work for the MSM driver, isn't it? > > Intel and AMD drivers don't allow to map the imported dma-bufs. Both > refuse to do the mapping. > > Although, AMDGPU "succeeds" to do the mapping using > AMDGPU_GEM_DOMAIN_GTT, but then touching the mapping causes bus fault, > hence mapping actually fails. I think it might be the AMDGPU > driver/libdrm bug, haven't checked yet.
That's then certainly broken somehow. Amdgpu should nerve ever have allowed to mmap() imported DMA-bufs and the last time I check it didn't.
Regards, Christian.
> > So we're back to the point that neither of DRM drivers need to map > imported dma-bufs and this was never tested. In this case this patch is > valid, IMO. >
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