Re: [PATCH v3 1/1] Support per-head resolutions with virtio-gpu

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Sep 02, 2025 at 02:13:12PM +0000, Andrew Keesler wrote:
> In 454f4b0f, we started down the path of supporting separate
> configurations per display head (e.g., you have 2 heads - one with
> EDID name "AAA" and the other with EDID name "BBB").
> 
> In this change, we add resolution to this configuration surface (e.g.,
> you have 2 heads - one with resolution 111x222 and the other with
> resolution 333x444).
> 
>   -display vnc=localhost:0,id=aaa,display=vga,head=0 \
>   -display vnc=localhost:1,id=bbb,display=vga,head=1 \
>   -device '{"driver":"virtio-vga",
>             "max_outputs":2,
>             "id":"vga",
>             "outputs":[
>               {
>                  "name":"AAA",
>                  "xres":111,
>                  "yres":222
>               },
>               {
>                  "name":"BBB",
>                  "xres":333,
>                  "yres":444
>               }
>             ]}'
> 
> Here is the behavior matrix of the current resolution configuration
> surface (xres/yres) with the new resolution configuration surface
> (outputs[i].xres/yres).
> 
> Case: !(xres || yres) && !(outputs[i].has_xres && outputs[i].has_yres)
> Behavior: current behavior - outputs[0] enabled with default xres/yres
> 
> Case: (xres || yres) && !(outputs[i].has_xres && outputs[i].has_yres)
> Behavior: current behavior - outputs[0] enabled with xres/yres
> 
> Case: !(xres || yres) && (outputs[i].has_xres && outputs[i].has_yres)
> Behavior: new behavior - outputs[i] enabled with outputs[i].xres/yres
> 
> Case: (xres || yres) && (outputs[i].has_xres && outputs[i].has_yres)
> Behavior: new behavior - outputs[i] enabled with outputs[i].xres/yres

This commit lacks the Signed-off-by line to assert compliance
with the DCO. Assuming  you agree, can you just reply to this
mail with your S-o-b and then I'll queue this.

> ---
>  hw/display/virtio-gpu-base.c | 10 ++++++++++
>  qapi/virtio.json             | 10 ++++++++--
>  2 files changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/display/virtio-gpu-base.c b/hw/display/virtio-gpu-base.c
> index 7269477a1c..6adb5312a4 100644
> --- a/hw/display/virtio-gpu-base.c
> +++ b/hw/display/virtio-gpu-base.c
> @@ -233,6 +233,16 @@ virtio_gpu_base_device_realize(DeviceState *qdev,
>      g->req_state[0].width = g->conf.xres;
>      g->req_state[0].height = g->conf.yres;
>  
> +    for (output_idx = 0, node = g->conf.outputs;
> +         node && output_idx < g->conf.max_outputs;
> +         output_idx++, node = node->next) {
> +        if (node->value->has_xres && node->value->has_yres) {
> +            g->enabled_output_bitmask |= (1 << output_idx);
> +            g->req_state[output_idx].width = node->value->xres;
> +            g->req_state[output_idx].height = node->value->yres;
> +        }
> +    }
> +
>      g->hw_ops = &virtio_gpu_ops;
>      for (i = 0; i < g->conf.max_outputs; i++) {
>          g->scanout[i].con =
> diff --git a/qapi/virtio.json b/qapi/virtio.json
> index 9d652fe4a8..9469c63e81 100644
> --- a/qapi/virtio.json
> +++ b/qapi/virtio.json
> @@ -966,15 +966,21 @@
>  ##
>  # @VirtIOGPUOutput:
>  #
> -# Describes configuration of a VirtIO GPU output.
> +# Describes configuration of a VirtIO GPU output. If both xres and
> +# yres are set, they take precedence over root virtio-gpu
> +# resolution configuration and enable the corresponding output.
>  #
>  # @name: the name of the output
>  #
> +# @xres: horizontal resolution of the output in pixels (since 10.2)
> +#
> +# @yres: vertical resolution of the output in pixels (since 10.2)
> +#
>  # Since: 10.1
>  ##
>  
>  { 'struct': 'VirtIOGPUOutput',
> -  'data': { 'name': 'str' } }
> +  'data': { 'name': 'str', '*xres': 'uint16', '*yres': 'uint16' } }
>  
>  ##
>  # @DummyVirtioForceArrays:
> -- 
> 2.51.0.338.gd7d06c2dae-goog
> 

With regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|