Re: [PATCH v7 7/9] drm/virtio: Improve DMA API usage for shmem BOs

[Emil Velikov]

On 2022/07/05, Gerd Hoffmann wrote:
>   Hi,
> 
> > > Also note that pci is not the only virtio transport we have.
> > 
> > The VirtIO indeed has other transports, but only PCI is really supported
> > in case of the VirtIO-GPU in kernel and in Qemu/crosvm, AFAICT. Hence
> > only the PCI transport was tested.
> 
> qemu -M microvm \
>   -global virtio-mmio.force-legacy=false \
>   -device virtio-gpu-device
> 
> Gives you a functional virtio-gpu device on virtio-mmio.
> 
> aarch64 virt machines support both pci and mmio too.
> s390x has virtio-gpu-ccw ...
> 

As the last person who was there - the problem is indeed when using
virtio on top of mmio. If that's no longer supported by the kernel then
the hacky code-path can be dropped.

Even in that case, I would suggest keeping it a separate commit.

HTH
Emil