[Spice-devel] [spice-server] doc: Add virgl documentation

[Cole Robinson]

I'm trying to test this stuff at the moment. Some comments and questions below
(not an ACK or NACK, I see the patch was already pushed)

On 03/18/2016 12:12 PM, Christophe Fergeau wrote:
> Document how to use virgl with QEMU/libvirt
> 
> virt-manager documentation still needs to be added.
> ---
>  docs/manual/manual.txt | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 55 insertions(+)
> 
> diff --git a/docs/manual/manual.txt b/docs/manual/manual.txt
> index 2c0035a..a89a702 100644
> --- a/docs/manual/manual.txt
> +++ b/docs/manual/manual.txt
> @@ -901,6 +901,61 @@ folder will show up in GNOME Files network places (or Nautilus). It
>  can then be mounted and browsed in traditional applications thanks to
>  `gvfs-fuse`.
>  
> +GL acceleration (virgl)
> +=======================
> +
> +OpenGL acceleration is currently local only (it has to go through a Unix socket)
> +and it needs guest support. It's currently limited to recent linux
> +distributions (for example up to date Fedora 23).
> +

The Fedora 23 reference isn't true and likely won't ever be true. The hard
requirements are looking like

- not-yet-released qemu 2.6 (won't ever be in f23)
- not-yet-released libvirt 1.3.3 (won't ever be in f23)
- not-yet-released spice 1.13.1 (likely not in f23)
- f23 era virgl and mesa bits

Speaking of which, what's the timeline for spice 1.13.1 release?

> +Configuration
> +-------------
> +
> +.Using libvirt
> +
> +You need to add a virtio-gpu video device to your virtual machine instead of QXL.
> +[source,xml]
> +<video>
> +  <model type='virtio' heads='1'>
> +    <acceleration accel3d='yes'/>
> +  </model>
> +</video>
> +
> +Then you need to enable OpenGL on your SPICE graphics node:
> +[source,xml]
> +<graphics type='spice' autoport='no'>
> +  <gl enable='yes'/>
> +</graphics>
> +
> +You don't need any port/address as they won't be usable with
> +GL.
> +

But this in fact won't work because we are dependent on spice+unix socket
bits, right? Which isn't implemented for libvirt yet and likely won't
committed for 1.3.3 either.

Even more, I feel like libvirt should reject a config like the above one
because it's kinda meaningless... with default qemu.conf settings that's
effectively listen=127.0.0.1 autoport=no which should raise an error since we
have no port to specify.

Slightly related question: what is the timeline for working gl passthrough
with local host + VM + spice listen=127.0.0.1 ? Is it under heavy development
or just waiting for just waiting for some new releases? If the latter, which
packages will be required?

> +.Using QEMU
> +
> +You need to add a virtio-gpu device on QEMU command line,
> +as well as enable GL with SPICE. port/tls-port/addr arguments
> +won't be used in this setup. You need to configure a Unix socket to
> +connect to the VM display.
> +
> +[source,sh]
> +-device virtio-vga,virgl=on -spice gl=on,unix,addr=/run/user/1000/spice.sock
> +
> +Connecting to the guest
> +-----------------------
> +
> +Connecting to the guest when virgl is in use is slightly different
> +than usual
> +
> +.If libvirt is being used
> +
> +[source,sh]
> +client$ virt-viewer -a $vmname
> +
> +.If a Unix socket has been set on QEMU command line
> +

Just a note, maybe someone should look into virt-viewer using -a automatically
when it sees a unix socket in the XML that it can't directly access

- Cole