[libvirt] [Qemu-devel] Re: Libvirt debug API

Daniel P. Berrange berrange at redhat.com
Mon Apr 12 13:05:19 UTC 2010

On Mon, Apr 12, 2010 at 01:23:08PM +0100, Jamie Lokier wrote:
> Daniel Veillard wrote:
> > On Sun, Apr 11, 2010 at 11:17:38PM +0100, Jamie Lokier wrote:

> > > Parsing libvirt output and having to guess which option corresponds to
> > > what from the libvirt config sounds very fragile and also a rather
> > > large amount of effort for something which should be easy.
> > 
> >   it's not that easy because we change the way we build the command line
> > for qemu as qemu evolves. for example before and after the support for
> > -device there have been a lot of changes.
> I agree, which is why it's much less fragile if libvirt provides the
> individual parts to hooks/wrappers, if that's asked, rather than
> forcing the wrapper to parse libvirts output and guess what libvirt
> does from version to version.
> For sure, before and after -device, any script which is involved with
> those options will probably have to change.  But that's quite unusual.

I could easily see this changing again in the not too distant future.
eg, we might switch to writing out a temporary config file with all 
options and just passing qemu -readonly /var/lib/libvirt/qemu/guest.cfg
to avoid the QEMU arg parsing / escaping problems. Or we might stop
using command line at all for devices, and use monitor device_add to
setup all devices. Allowing ability to append extra args to the QEMU
command line is reasonably safe, while support for hooking into existing
command line args is not.

|: Red Hat, Engineering, London    -o-   http://people.redhat.com/berrange/ :|
|: http://libvirt.org -o- http://virt-manager.org -o- http://deltacloud.org :|
|: http://autobuild.org        -o-         http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505  -o-   F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|

More information about the libvir-list mailing list