Messages in this thread | | | Date | Wed, 6 Oct 2021 21:32:38 +0200 | From | Borislav Petkov <> | Subject | Re: `AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y` causes AMDGPU to fail on Ryzen: amdgpu: SME is not compatible with RAVEN |
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On Wed, Oct 06, 2021 at 02:21:40PM -0400, Alex Deucher wrote: > And just another general comment, swiotlb + bounce buffers isn't > really useful on GPUs. You may have 10-100s of MBs of memory mapped > long term into the GPU's address space for random access. E.g., you > may have buffers in system memory that the display hardware is > actively scanning out of. For GPUs you should really only enable SME > if IOMMU is enabled in remapping mode. But that is probably beyond > the discussion here.
Right, but insights into how these things work (or don't work) together are always welcome. And yes, as 2cc13bb4f59f says:
"... The bounce buffer code has an upper limit of 256kb for the size of DMA allocations, which is too small for certain devices and causes them to fail."
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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