Re: [PATCH] libxl: fix cirrus vga video memory setting with upstream qemu

[Fabio Fantoni <fabio.fantoni@m2r.biz>]

Il 09/05/2014 16:03, Stefano Stabellini ha scritto:
> On Fri, 9 May 2014, Ian Campbell wrote:
>> On Fri, 2014-05-09 at 10:01 +0200, Fabio Fantoni wrote:
>>> Il 08/05/2014 17:19, Ian Campbell ha scritto:
>>>> On Thu, 2014-05-08 at 17:03 +0200, Fabio Fantoni wrote:
>>>>> Il 08/05/2014 13:33, Ian Campbell ha scritto:
>>>>>> On Thu, 2014-05-08 at 12:41 +0200, Fabio Fantoni wrote:
>>>>>>
>>>>>>> About qemu version when vgamem_mb property is added is qemu 1.3, I
>>>>>>> already did detailed reply about it in stdvga patch:
>>>>>>> http://lists.xen.org/archives/html/xen-devel/2014-05/msg00259.html
>>>>>>> Or you mean something other?
>>>>>> "in the commit message" is the bit you keep missing.
>>>>> I not found 1399030886.32736.63.camel@kazak.uk.xensource.com with google
>>>>> or thunderbird on mail archive, I not understand what post you refer :(
>>>> mid.gmane.org is a good way to find these things. e.g.:
>>>> http://mid.gmane.org/<1399030886.32736.63.camel@kazak.uk.xensource.com>
>>>>
>>>> Note that the <> which I quoted *are* part of the message id.
>>>>
>>>> The questions there were:
>>>>           Is this change correct for all versions of mainline qemu which
>>>>           people might be using with Xen?
>>> vgamem_mb property was added in qemu 1.3 (same for stdvga patch),
>> How was the video RAM size controller in qemu prior to that? Or was it
>> not possible?
>>
>>>   xen
>>> 4.4 from source use qemu 1.6, and from distributions package is newer
>>> all case I saw, then FWIK there should be no problems. Xen 4.4 if I
>>> remember good change other important qemu value for hvm domUs that
>>> require qemu>=1.6. (1.6.1 because 1.6.0 have critical regression for all
>>> hvm domUs)
>> Stefano/Anthony -- can you confirm that we already depend on qemu >=
>> 1.6.x (or otherwise that it is OK to depend on qemu >= 1.3)?
>  From upstream QEMU POV anything older than 1.7 is "ancient" and
> unmaintained.
>
>  From Xen POV the upstream QEMU version that we released with Xen 4.2 was
> based on QEMU v1.0.1, the one we released with Xen 4.3 was based on
> v1.3.0.
>
> Given that upstream QEMU with Xen 4.2 was a tech preview and that if I
> am not mistaken we don't maintain Xen 4.2 anymore, it should be OK to
> depend on QEMU >= 1.3.

If I remember good the machine/pv qemu parameters part changed by 
Anthony in xen 4.4 require at least qemu 1.6.
In that case xen >=4.4 need already qemu>=1.6.1 (1.6.1 because 1.6.0 
have critical regression for all
hvm domUs)

>
>
>> An ack from you guys on this change would be appreciated.
> I think the change is OK but I wonder if we should write down somewhere,
> maybe in the 4.5 release notes or on the wiki, that we depend on QEMU >=
> 1.3.
>
>
>> It's also been proposed that we backport this to stable branches, how
>> far back would it be safe/acceptable for us to go with that?
>> [...]
> Anything newer than 4.2 should be OK.