Re: [PATCH 2/2] hw/display: Allow injection of virtio-gpu EDID name

[Daniel P . Berrangé]

On Mon, Nov 25, 2024 at 03:54:40PM -0500, Andrew Keesler wrote:
> I follow what you are saying. I misunderstood what a "display" was in the
> domain of QEMU. Yes, this makes more sense now.
> 
> > the user should give names for every output at startup
> 
> I see DEFINE_PROP_ARRAY exists. I can use that to define the new "outputs"
> property. Any reason that each "output" would ever need to be an object
> (rather than just a string)? Nothing comes to mind, I'm just taking a second
> to think about API forwards compatibility.

Currently we have 'xres' and 'yres' properties set against the device
for virtio-gpu.

If we're going to extend  it to allow the name of each "output" head
to be configured, it makes sense to allow for a data structure that
will let us also cnofigure xres & yres per output.

Hence, I thought it would make more sense to have an array of structs,
rather than the simpler array of strings, which will let us set any
amount of per-output config data we might want in future.

NB, I'm not asking you to wire up support for xres/yres per output,
just that we anticipate it as a possibility.

> > upto whatever they said for "max_outputs"
> 
> Where is the best place to perform this validation? I would imagine we would
> want to fast-fail if the user provided more "outputs" than "max_outputs". I
> can
> perform the validation in virtio_gpu_base_get_features but that seems late.

I'd suggest putting it in virtio_gpu_base_device_realize, as we already
have code there to validate 'max_outputs" is within limits.


With regards,
Daniel
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