Enhancement: Virtual OpenGL support (Virgl)
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One of the nice things with QEMU is a feature called Virgl. It uses the VirtIO-GPU driver on Linux guests to proxy OpenGL (and I read soon Vulkan) commands to the hosts GPU. This allows several guests to use HW acceleration using a single GPU on the host. It also allows the host to continue to use the CPU for console output.
Virgl isn't as fast as a GPU pass-through, but it is much more flexible and easier to manager. I am thinking that in a XCP-ng environment it could allow migrating guests while retaining HW acceleration.
For now, there is no VirtIO-GPU support in Xen, but I saw some talk from 2016 about it on te Xen mailing lists. https://lists.xenproject.org/archives/html/xen-devel/2016-01/msg03309.html
I am not thinking it would be an easy task to implement, but it would bring some unique capabilities to XCP-ng and could prove valuable for XCP-ng users, especially if a VirtIO-GPU driver for Windows guests materialise.
https://virgil3d.github.io/
https://www.dedoimedo.com/computers/qemu-virgil.html
https://cgit.freedesktop.org/virglrenderer -
First, you need virtIO in XCP-ng
(which isn't the case at all yet). However, we have an intern who started to work on that since last week 
After getting virtIO (if it's possible with a reasonable effort), then we could start to see for the rest of virtIO perks.
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I'm happy to hear you are working on VirtIO since both FreeBSD and Linux guests supports it well these days.
Obviously this is a big commitment, but I thought I'd post about it anyway in the hopes that it could one day become possible
One more thing that would be needed for virtio is spice support. This would actually be pretty cool as it allows piping USB, Audio and VGA to users connecting to the VM's console
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Hi, how is it going with the virtio stuff? I think it could really benefit the XCP-ng ecosystem to have VirtIO with the possibilities it may bring. For example usermode networking with ovs, virtiofs (file sharing with host/dom0) and of course VirGL
VirGL is useful because it provides accelerated OpenGL on multiple guests at the same time.Obviously if you run it on multiple guests it affects the performance, but I think it is a trade-off worth having. Most desktop environments on Linux uses acceleraded GL, so it would improve normal desktop performance as well.
Here is an example of Linux Mint running Unigine Heaven on VirGL over Spice with sound (remote-viewer) over WiFi. The host is an AMD Athlon 3000G 2 core with integrated graphics. The CPU was only $50 when released many years ago - to give some perspective on its performance.
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We are not directly monitoring the virtio stuff in Xen Project, but you should see some progress on the mailing list
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virtIO in xen, now that would be great!
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It might be happening after all
https://www.phoronix.com/news/AMD-Xen-GPU-For-Cars
https://www.phoronix.com/news/AMD-GPU-Xen-Hypervisor-S3
Having virtio gpu with gl/vulkan/dx3d support would be really interesting.
