Re: [PATCH v3 4/4] drm/virtio: Support virtgpu exported resources

From: Michael S. Tsirkin
Date: Mon Jun 08 2020 - 05:43:38 EST


On Fri, May 15, 2020 at 04:26:15PM +0900, David Stevens wrote:
> > > + if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_RESOURCE_UUID)) {
> > > + vgdev->has_resource_assign_uuid = true;
> > > + }
> >
> >
> > Just a question: this relies on DMA bufs so I assume it is
> > not really assumed to work when DMA API is bypassed, right?
> > Rather than worry what does it mean, how about just
> > disabling this feature without PLATFORM_DMA for now?
>
> By PLATFORM_DMA, do you mean CONFIG_DMA_SHARED_BUFFER?

Sorry, no. I mean VIRTIO_F_IOMMU_PLATFORM which in the
future will be renamed to VIRTIO_F_PLATFORM_ACCESS.


> Virtio-gpu
> depends on DRM, which selects that feature. So I think DMA bufs should
> always be available when virtio-gpu is present.
>
> -David