Re: [Xen-devel] Correct format for HVM graphics

[Stefan Bader <stefan.bader@xxxxxxxxxxxxx>]

On 05.04.2012 17:29, Stefano Stabellini wrote:
> On Thu, 5 Apr 2012, Stefan Bader wrote:
>>> In any case, as I said before, if the alternatives are keeping the wait
>>> time or patching xend, I would go for patching xend.
>>> If we don't think we can fix Linux and backport the fix in a reasonable
>>> time, patching xend might be the only option.
>>
>> My impression is that you (the generic you) would not really want to modify 
>> xend
>> too much as it and the xm stack should go away anyway.
>> Instead I would fix libvirt's use of xend when it is known that it is not
>> working well (if using "vfb = [ 'vnc=1, ...' ]" or similar for sxpr is 
>> creating
>> a vkbd and xend/the xm stack does not support it, then just don't use it).
>>
>> The question of removing the delays is not so much (well yes it is too, but 
>> not
>> always in ones own hands) whether it can be done or how quickly. Providing 
>> the
>> means to run guests is something rather under our control. Be it Ubuntu as 
>> dom0
>> or Xenserver. But which kernels are run as guests is not.
>>
>> So, as long as xend does not change its behavior, then changing libvirt in a 
>> way
>> that does never use the configuration format which causes a vkbd to be 
>> created
>> (for HVM) is ok. And if it gets picked up upstream it helps all users of 
>> libvirt
>> the same.
>> But if xend would change to allow using a vkbd, then it would be good if that
>> could be synced with a xend version change which could be used inside 
>> libvirt to
>> modify its config output (as it does now but in some way with the wrong 
>> version).
>>
>> The kernel change to remove delays imo is a completely separate issue. And if
>> just as an additional "pre-caution".
> 
> So the argument is that ATM libvirt uses a vfb config line with HVM
> guests and that is wrong.

Yes! :)

> I agree with you there, the vfb config line is for PV guests only and
> should be removed from any HVM guests configurations.
> In fact, even if we add a vfb frontend/backend pair for HVM guests, it
> probably won't go through a vfb config line, because the vnc/sdl
> configuration would be shared between the vfb and vga devices.
> 
> So you convinced me that is OK to remove it from libvirt :-)

Ok, then I try to convince them as well. :) Actually I think we were agreeing
most of the time... just not always about the same thing. ;) Which is probably
due to me trying to wrap the issue into too many words...

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