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Re: [libvirt] [PATCH 4/6] Canonicalize qemu machine types



On Mon, Jul 27, 2009 at 03:11:10PM +0100, Mark McLoughlin wrote:
> On Mon, 2009-07-27 at 15:42 +0200, Daniel Veillard wrote:
> > On Thu, Jul 23, 2009 at 06:34:42PM +0100, Mark McLoughlin wrote:
> > > In qemu-0.11 there is a 'pc-0.10' machine type which allows you to run
> > > guests with a machine which is compatible with the pc machine in
> > > qemu-0.10 - e.g. using the original PCI class for virtio-blk and
> > > virtio-console and disabling MSI support in virtio-net. The idea here
> > > is that we don't want to suprise guests by changing the hardware when
> > > qemu is updated.
> > > 
> > > I've just posted some patches for qemu-0.11 which allows libvirt to
> > > canonicalize the 'pc' machine alias to the latest machine version.
> > > 
> > > This patches makes us use that so that when a guest is configured to
> > > use the 'pc' machine type, we resolve that to 'pc-0.11' machine and
> > > save that in the guest XML.
> > > 
> > > See also:
> > > 
> > >   https://fedoraproject.org/wiki/Features/KVM_Stable_Guest_ABI
> > > 
> > > * src/qemu_conf.c: add qemudCanonicalizeMachine() to canonicalize
> > >   the machine type according to the machine aliases in capabilities
> > > 
> > [...]
> > >  /* Format is:
> > > - * <machine> <desc> [(default)]
> > > + * <machine> <desc> [(default)|(alias of <canonical>)]
> > >   */
> > >  static int
> > >  qemudParseMachineTypesStr(const char *output,
> > > @@ -319,6 +319,15 @@ qemudParseMachineTypesStr(const char *output,
> > >              list[0] = machine;
> > >              nitems++;
> > >          }
> > > +
> > > +        if ((t = strstr(p, "(alias of ")) && (!next || t < next)) {
> > > +            p = t + strlen("(alias of ");
> > > +            if (!(t = strchr(p, ')')) || (next && t >= next))
> > > +                continue;
> > > +
> > > +            if (!(machine->canonical = strndup(p, t - p)))
> > > +                goto error;
> > > +        }
> > >      } while ((p = next));
> > 
> >   hum, if you get (alias of  foo ) your canonical will end up being
> > " foo " instead of "foo" maybe spaces should be stripped before and
> > after the name (i.e. it would have been perfect in an XML attribute but
> > well ...)
> 
> If only we had something like g_strstrip() :-)

  oh, I'm sure we have something like that in libxml2 but the name is
probably even worse :-)

> > [...]
> > > +static int
> > > +qemudCanonicalizeMachineFromInfo(virDomainDefPtr def,
> > > +                                 virCapsGuestDomainInfoPtr info,
> > > +                                 char **canonical)
> > > +{
> > > +    int i;
> > > +
> > > +    *canonical = NULL;
> > > +
> > > +    for (i = 0; i < info->nmachines; i++) {
> > > +        virCapsGuestMachinePtr machine = info->machines[i];
> > > +
> > > +        if (!machine->canonical)
> > > +            continue;
> > > +
> > > +        if (strcmp(def->os.machine, machine->name) != 0)
> > > +            continue;
> > > +
> > > +        if (!(*canonical = strdup(machine->canonical)))
> > 
> >   virReportOOMError(NULL) please :-)
> 
> Yep, thanks.

  np :-)

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/


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