Re: [Qemu-devel] Re: [PATCH 1/1] Add -version-simple argument, printing only version number.

[Chris Lalancette <clalance@redhat.com>]

On 05/14/2010 09:21 AM, Anthony Liguori wrote:
> On 05/13/2010 03:32 AM, Jes.Sorensen@redhat.com wrote:
>> From: Jes Sorensen<Jes.Sorensen@redhat.com>
>>
>> Add -version-simple argument for QEMU, printing just the version
>> number, without any supporting text.
>>    
> 
> I'm not a huge fan of the name.
> 
> But what information are we trying to convey?  Just major/minor number
> or would qemu-kvm also throw some info in there?
> 
> Do version numbers even matter because 0.13 from qemu.git is going to be
> a hell of a lot different from 0.13 in RHEL6.x.
> 
> What are the consumers of this information actually doing with it?

At the moment libvirt uses it mostly to determine what features are
present in a particular version of Qemu that is on the machine.  So
for instrance, for 0.13 we turn on the JSON flag so we know to use
the QMP monitor instead of the text monitor.  There are many other
examples as well.

Now, I agree that this isn't the best way to do it; much better would
be a way for libvirt to query the capabilities of Qemu directly and
not rely on versions (not the least because of the problem you point
out above).  But up until now we haven't had a better way to do it.

-- 
Chris Lalancette