On Fri, Feb 12, 2021 at 08:15:12AM +0000, Kasireddy, Vivek wrote: > Hi Gerd, > > > > > You don't have to use the rendering pipeline. You can let the i915 > > > > gpu render into a dma-buf shared with virtio-gpu, then use > > > > virtio-gpu only for buffer sharing with the host. > [Kasireddy, Vivek] Just to confirm my understanding of what you are suggesting, are > you saying that we need to either have Weston allocate scanout buffers (GBM surface/BO) > using virtio-gpu and render into them using i915; or have virtio-gpu allocate pages and > export a dma-buf and have Weston create a GBM BO by calling gbm_bo_import(fd) and > render into the BO using i915? Not sure what the difference between the former and the latter is. > > Hmm, why a big mode switch? You should be able to do that without modifying the > > virtio-gpu guest driver. On the host side qemu needs some work to support the most > > recent virtio-gpu features like the buffer uuids (assuming you use qemu userspace), right > > now those are only supported by crosvm. > [Kasireddy, Vivek] We are only interested in Qemu UI at the moment but if we were to use > virtio-gpu, we are going to need to add one more vq and support for managing buffers, > events, etc. Should be easy and it should not need any virtio-gpu driver changes. You can use virtio-gpu like a dumb scanout device. Create a dumb bo, create a framebuffer for the bo, map the framebuffer to the crtc. Then export the bo, import into i915, use it as render target. When rendering is done flush (DRM_IOCTL_MODE_DIRTYFB). Alternatively allocate multiple bo's + framebuffers and pageflip. Pretty standard workflow for cases where rendering and scanout are handled by different devices. As far I know not uncommon in the arm world. Right now this will involve a memcpy() for any display update because qemu is a bit behind on supporting recent virtio-gpu features. take care, Gerd _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
