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

["Daniel P. Berrange" <berrange@redhat.com>]

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.

Daniel
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