On Fri, Mar 01, 2013 at 03:58:18PM -0300, Eduardo Habkost wrote:
On Fri, Mar 01, 2013 at 07:31:46PM +0100, Andreas Färber wrote:
Am 01.03.2013 14:12, schrieb Jiri Denemark:
On Thu, Feb 21, 2013 at 11:58:18 -0300, Eduardo Habkost wrote:
= Listing CPU models =
Requirement: libvirt needs to know which CPU models are available to be used with the "-cpu" option.
Current problem: libvirt relies on help output parsing for that.
query-cpu-definitions is the QMP command to retrieve values compatible with -cpu.
And if libvirt is not using it, I really don't understand why the work of maintaining this crappy interface has been pushed onto us in the first place? There is no reuse between -cpu ? and QMP implementations so it's just extra work, there is no communicated or implemented way to extend the arch_query_cpu_definitions() implementation to become more usable for command line output implementation (e.g., associating a PVR value with the model name for ppc) and, while we're at it, it uses global functions plus a stub rather than a CPUState hook with a no-op default implementation in qom/cpu.c...
I have the same questions you have. :-)
But my main complaint about query-cpu-definitions is not about the implementation: it's that the interface was introduced without taking into account the requirements of libvirt regarding CPU features. It was found to be not appropriate for what libvirt needs[1], but somehow it got applied anyway.
The requirement at the time we did this was just to have a straight adaptation of the stuff libvirt parsed from -help, into QMP format. The query-cpu-definitions command served that purpose fine. It was expected that some of this may be sub-optimal in the long term. This is fine - we can either extend the existing data, or introduce brand new commands to deal with the problems. The key thing was just to get 100% into the QMP world for capabilities at that time, and then iterate to improve things. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|