Re: [PATCH v4 1/1] Support per-head resolutions with virtio-gpu

[Markus Armbruster <armbru@redhat.com>]

Sorry for the delay.  Recovering from the coughing plague.

Andrew Keesler <ankeesler@google.com> writes:

> 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
>
> Signed-off-by: Andrew Keesler <ankeesler@google.com>

[...]

> diff --git a/qapi/virtio.json b/qapi/virtio.json
> index cd67c4f52e..c1a1fb4997 100644
> --- a/qapi/virtio.json
> +++ b/qapi/virtio.json
> @@ -970,15 +970,24 @@
>  ##
>  # @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.  If
> +# only one or none of @xres or @yres is set, root virtio-gpu
> +# resolution configuration takes precedence and only the first output
> +# is enabled.

So when exactly one of @xres or @yes is present, it's silently ignored?

>  #
>  # @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 11.0)

> +#
>  # Since: 10.1
>  ##
>  
>  { 'struct': 'VirtIOGPUOutput',
> -  'data': { 'name': 'str' } }
> +  'data': { 'name': 'str', '*xres': 'uint16', '*yres': 'uint16' } }
>  
>  ##
>  # @DummyVirtioForceArrays: