Re: [Qemu-devel] QEMU: PCI bus name on PowerPC platforms

[Eric Blake <eblake@redhat.com>]

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On 04/11/2014 05:40 AM, Alexey Kardashevskiy wrote:

>> but AFAICT nothing got merged to change this for all the other boards as
>> discussed here :-(  This is painful for libvirt since we have todo even
>> more hacks triggered off machine names now, instead of being able to
>> rely on pci.0 naming as we hoped.
> 
> Sorry, I am missing the point.
> How could making a platform similar to many others force you to do more
> hacks, not less?

As mentioned in the thread here:
https://lists.gnu.org/archive/html/qemu-devel/2014-04/threads.html#01565

If there is a way to query via QMP to see which naming scheme is in
effect, there are no hacks involved - we just ask and get it right.

If ALL platforms behave identically as of a certain release, we have a
minimal hack - catering to releases older than that, where a downstream
backport may have to tweak how we detect older releases, but it is only
a single place to be hacked.

But with just this patch, you have caused the situation where it is
neither introspectible, nor consistent across qemu versions.  The only
way to code that up in libvirt is to do MULTIPLE version checks and
correlate it with architecture checks - and that's the hack we don't
want to have to support.  Every single version check done in lieu of
proper feature introspection is yet one more pain point when features
get backported across version numbers downstream.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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