Re: [PATCH qemu-server v4 1/3] fix #6277: virtio-vga-gl: add OpenGL 4.6 and Vulkan (Venus) support

["DERUMIER, Alexandre" <alexandre.derumier@groupe-cyllene.com>]

Hi,
thanks for the patch serie!

I'll rebase my kyber console patches serie over it, as I was adding
venus support

https://lore.proxmox.com/pve-devel/20260826074347.1256659-6-alexandre.derumier@groupe-cyllene.com/T/#u


One question, I didn't need virgl-server to enable venus and get it
work with gpu offloading from my amd gpu.
Maybe is it because I'm using dbus display for output ?

(I really don't known how virgl-server to be honest, dont have read the
doc yet)

Best regards,

Alexandre


Le lundi 31 août 2026 à 11:38 +0200, Markus Frank a écrit :
> Adding the 'blob=on,hostmem=<size>' parameters to the 'virtio-gpu-gl'
> device allows the VM to use OpenGL 4.6. By default virtio-gpu-gl only
> supports up to OpenGL 4.3.
> 
> If Vulkan support is needed, the 'venus=on' parameter is added to the
> 'virtio-gpu-gl' device, in addition to the two parameters required
> for
> OpenGL 4.6.
> 
> The Venus protocol facilitates the translation of Vulkan API calls
> via
> the virglrenderer. To use it, the virgl-server package must be
> installed
> on the host.
> 
> Set the default VirGL memory window to 2048 MiB, as having less could
> lead to instability inside the VM.
> 
> Signed-off-by: Markus Frank <m.frank@proxmox.com>
> ---
> v4:
> * made the description of virgl-features more general
> * added bugzilla number to commit message
> 
>  src/PVE/QemuServer.pm | 36 +++++++++++++++++++++++++++++++++++-
>  1 file changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/src/PVE/QemuServer.pm b/src/PVE/QemuServer.pm
> index 63d8c135..65c4a804 100644
> --- a/src/PVE/QemuServer.pm
> +++ b/src/PVE/QemuServer.pm
> @@ -171,6 +171,20 @@ my $vga_fmt = {
>              qw(cirrus qxl qxl2 qxl3 qxl4 none serial0 serial1
> serial2 serial3 std virtio virtio-gl vmware)
>          ],
>      },
> +    'virgl-features' => {
> +        description => 'Enable additional features on VirGL GPU.',
> +        type => 'string',
> +        optional => 1,
> +        enum => ['opengl4.6', 'opengl4.6+vulkan'],
> +    },
> +    'virgl-memory-window' => {
> +        description => 'Set the VirGL host memory window. This
> option allocates'
> +            . ' host memory to act as VRAM in the VM.',
> +        type => 'string',
> +        default => '2048',
> +        optional => 1,
> +        enum => ['512', '1024', '2048', '4096', '8192'],
> +    },
>      memory => {
>          description => "Sets the VGA memory (in MiB). Has no effect
> with serial display.",
>          type => 'integer',
> @@ -1549,6 +1563,23 @@ sub print_vga_device {
>          $pciaddr = print_pci_addr($vgaid, $bridges, $arch);
>      }
>  
> +    my $virgl_param = "";
> +    my $virgl_mode = $vga->{'virgl-features'};
> +    if ($virgl_mode) {
> +        my $virgl_memory_window = $vga->{'virgl-memory-window'}
> +            // $vga_fmt->{'virgl-memory-window'}->{'default'};
> +        $virgl_param = ",hostmem=${virgl_memory_window}M,blob=on";
> +
> +        if ($virgl_mode eq 'opengl4.6+vulkan') {
> +            $virgl_param .= ",venus=on";
> +            log_warn(
> +                "missing virgl render server for Vulkan (Venus)
> support! Please install 'virgl-server'.\n"
> +            ) if !-e "/usr/libexec/virgl_render_server";
> +        }
> +    } elsif ($vga->{'virgl-memory-window'}) {
> +        die "To use a VirGL host memory window, please select a
> compatible VirGL feature set.\n";
> +    }
> +
>      if ($vga->{type} eq 'virtio-gl') {
>          # VirGL renders on the host, so the guest arch is irrelevant
> for the library lookup
>          my $host_arch = get_host_arch();
> @@ -1560,9 +1591,12 @@ sub print_vga_device {
>          die
>              "no DRM render node detected (/dev/dri/renderD*), no
> GPU? - needed for '$vga->{type}' display\n"
>              if !PVE::Tools::dir_glob_regex('/dev/dri/',
> "renderD.*");
> +
> +    } elsif ($virgl_mode) {
> +        die "You need to use virtio-gl to enable OpenGL 4.6 or
> Vulkan support!\n";
>      }
>  
> -    return
> "$type,id=${vgaid}${memory}${max_outputs}${pciaddr}${edidoff}";
> +    return
> "$type,id=${vgaid}${memory}${max_outputs}${pciaddr}${edidoff}${virgl_
> param}";
>  }
>  
>  sub vm_is_volid_owner {