[libvirt] [PATCH] qemu: Detect VGA_QXL capability correctly

[Michal Privoznik]

On 04.01.2013 15:06, Guannan Ren wrote:
> On 01/04/2013 05:00 PM, Michal Privoznik wrote:
>> Since 4c993d8a we failed to set this important capability, which
>> allows starting a domain with QXL video card. We set DEVICE_QXL
>> capability bit instead, which is not necessary wrong. Anyway, if
>> qemu supports the new '-device qxl' it supports older '-vga qxl'
>> as well. The latter is used for the primary (the first) qxl video
>> card, the former for other video cards.
>> ---
>>
>> Other approach is to set QEMU_CAPS_VGA_QXL unconditionally
>> as supported by all qemu-1.2+ in qemuCapsInitQMPBasic().
>> But I think this one is slightly nicer.
>>
>>   src/qemu/qemu_capabilities.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
>> index f49a31c..e16bc70 100644
>> --- a/src/qemu/qemu_capabilities.c
>> +++ b/src/qemu/qemu_capabilities.c
>> @@ -2018,6 +2018,9 @@ qemuCapsProbeQMPObjects(qemuCapsPtr caps,
>>       /* Prefer -chardev spicevmc (detected earlier) over -device
>> spicevmc */
>>       if (qemuCapsGet(caps, QEMU_CAPS_CHARDEV_SPICEVMC))
>>           qemuCapsClear(caps, QEMU_CAPS_DEVICE_SPICEVMC);
>> +    /* If qemu supports newer -device qxl it supports -vga qxl as
>> well */
>> +    if (qemuCapsGet(caps, QEMU_CAPS_DEVICE_QXL))
>> +        qemuCapsSet(caps, QEMU_CAPS_VGA_QXL);
>>         return 0;
>>   }
> 
>     I don't think it is necessary to add this code.
>     because we have set the caps flag in qemuCapsParseHelpStr()
> 
>             if (strstr(p, "|qxl"))
>             qemuCapsSet(caps, QEMU_CAPS_VGA_QXL);

which is not called if capabilities are initialized via QMP.

> 
>     The problem here is about collecting cap flags via QMP, we need to
> set QEMU_CAPS_VGA_QXL
>     unconditionally but still in discussion.
> 
>   Patch from Doug Goldstein in [libvirt] [PATCH] The -vga CLI arg
> accepts qxl in qemu 1.2+ always
> 
> The -vga command always accepts qxl in 1.2 and newer.
> ---
>  src/qemu/qemu_capabilities.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index f49a31c..c3ab488 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -2282,6 +2282,7 @@ qemuCapsInitQMPBasic(qemuCapsPtr caps)
>      qemuCapsSet(caps, QEMU_CAPS_NO_USER_CONFIG);
>      qemuCapsSet(caps, QEMU_CAPS_NETDEV_BRIDGE);
>      qemuCapsSet(caps, QEMU_CAPS_SECCOMP_SANDBOX);
> +    qemuCapsSet(caps, QEMU_CAPS_VGA_QXL);
>  }
> 

I don't think it should be set unconditionally neither. I know I wrote
it under commit message, but now re-thinking it again - what if somebody
builds his own qemu without QXL?

Michal