Re: [Qemu-devel] [PATCH 1/8] virtio-gpu/2d: add hardware spec include file

[Dave Airlie]

On 15 October 2014 20:05, Gerd Hoffmann <address@hidden> wrote:
>   Hi,
>
>> +/* VIRTIO_GPU_RESP_OK_DISPLAY_INFO */
>> +#define VIRTIO_GPU_MAX_SCANOUTS 16
>> +struct virtio_gpu_resp_display_info {
>> +    struct virtio_gpu_ctrl_hdr hdr;
>> +    struct virtio_gpu_display_one {
>> +        uint32_t enabled;
>> +        uint32_t width;
>> +        uint32_t height;
>> +        uint32_t x;
>> +        uint32_t y;
>> +        uint32_t flags;
>> +    } pmodes[VIRTIO_GPU_MAX_SCANOUTS];
>
> One more thing: I think it would be a good idea to add the display
> resolution here.  We start seeing highres displays on desktops, and the
> guest should know whenever the host display runs at 100 or 300 dpi ...
>
> What do you think?

Passing host display side into the guest isn't going to help, unless
you are running in full screen,

I suppose the guest could adjust the numbers, but what happens with
viewers, if I connect on a hidpi and move to a lodpi screen.

I think this would require a lot more thought in how it would work in
some use-cases.

That said reserving 2 32 bit fields for possible screen measurements
might future proof things a little, though most OSes use EDID to detect
this sort of thing, so we might not find a great use for it later.

Dave.