Re: [Qemu-devel] [RFC PATCH spice v2 1/2] QXL interface: add functions to identify monitors in the guest

[Lukáš Hrázký]

On Mon, 2018-11-05 at 07:52 +0100, Gerd Hoffmann wrote:
> > 2. Have a single function as follows:
> > 
> > void spice_qxl_set_device_info(QXLInstance *instance,
> >                                const char *device_address,
> >                                uint32_t device_display_id_start,
> >                                uint32_t device_display_id_count);
> 
> How about:
> 
> void spice_qxl_set_device_info(QXLInstance *instance,
>                                const char *device_address,
>                                uint32_t device_display_id);
> 
> I don't think we need start+count:
> 
>  * For single-head devices device_display_id will be zero.
>  * For one-channel-per-head multihead devices (i.e. virtio-gpu)
>    device_display_id will enumerate the heads (so everybody can figure
>    which channel is which head).
>  * For one-channel-per-device multihead devices (i.e. qxl/linux)
>    device_display_id will be zero too.  Number of heads is set via
>    spice_qxl_set_max_monitors().

That requires nontrivial and unexpected logic for the one-channel-per-
device multihead devices case. The API should be doing what it says and
 the dumber the better, this seems too smart to me...

That said, I don't find it significantly worse than the other options
(none of which seems great), so I'd just like we reached some consesus
and be done with it...

Cheers,
Lukas

> cheers,
>   Gerd
>