Re: [Qemu-devel] [PATCH] RFC: qxl: allow to specify head limit to qxl driver

[Frediano Ziglio]

2015-06-09 10:12 GMT+01:00 Gerd Hoffmann <address@hidden>:
> On Di, 2015-06-09 at 09:49 +0100, Frediano Ziglio wrote:
>> This patch allow to limit number of heads using qxl driver. By default
>> qxl driver is not limited on any kind on head use so can decide to use
>> as much heads.
>
> There is a hard limit of 16 monitors in the qxl device ...
>

Ok, didn't see it.

>> Main question and stop over are parameter name.
>
> max_outputs please, to be consistent with upcoming virtio-vga.
>

I'll do.

>> +    if (d->max_heads && d->max_heads <= 64) {
>> +        rom->flags         = cpu_to_le64(QXL_ROM_FLAG_MAX_HEADS);
>> +        rom->max_heads     = cpu_to_le16(d->max_heads);
>> +    }
>
> rom does already carry information about the heads.  How about simply
> applying the limit when filling rom->client_monitors_config in
> interface_client_monitors_config()?
>
> No device changes, no driver changes, alot less trouble.
>
> cheers,
>   Gerd
>

So what you are proposing is client should limit heads based on
spice-server limit and also spice-server should limit monitor received
from client. I'll try it. So this would require only Qemu + libvirt
change. This is slightly change anyway as guest will see more heads
without monitor connected instead of limiting heads. But anyway is a
way to enforce heads.

Frediano