On 10/11/21 8:11 AM, Borislav Petkov wrote:
On Mon, Oct 11, 2021 at 03:05:33PM +0200, Paul Menzel wrote:
I think, the IOMMU is enabled on the MSI B350M MORTAR, but otherwise, yes
this looks fine. The help text could also be updated to mention problems
with AMD Raven devices.
This is not only about Raven GPUs but, as Alex explained, pretty much
about every device which doesn't support a 48 bit DMA mask. I'll expand
that aspect in the changelog.
In general, non-GPU devices that don't support a 48-bit DMA mask work fine
(assuming they have set their DMA mask appropriately). It really depends
on whether SWIOTLB will be able to satisfy the memory requirements of the
driver when the IOMMU is not enabled or in passthrough mode. Since GPU
devices need/use a lot of memory, that becomes a problem.
Thanks,
Tom
