[libvirt] [PATCH] qemu: add PCI-multibus support for ppc

[Hong-Hua.Yin at freescale.com]

Daniel,

I got it. We need do machine detection for the special PPC platforms. 
Thank you for comments.

Olivia
> -----Original Message-----
> From: Daniel P. Berrange [mailto:berrange at redhat.com]
> Sent: Tuesday, March 04, 2014 10:53 PM
> To: Yin Olivia-R63875
> Cc: libvir-list at redhat.com
> Subject: Re: [PATCH] qemu: add PCI-multibus support for ppc
> 
> On Fri, Feb 28, 2014 at 09:10:47AM +0000, Hong-Hua.Yin at freescale.com wrote:
> > Hi Daniel,
> >
> > Refer to libvirt/src/qemu/qemu_capabilities.c, only x86_64/i686 support
> PCI_MULTIBUS.
> >     /* Currently only x86_64 and i686 support PCI-multibus. */
> >     if (qemuCaps->arch == VIR_ARCH_X86_64 ||
> >         qemuCaps->arch == VIR_ARCH_I686) {
> >         virQEMUCapsSet(qemuCaps, QEMU_CAPS_PCI_MULTIBUS);
> >
> > libvirt/src/qemu/qemu_capabilities.h:
> >     QEMU_CAPS_PCI_MULTIBUS       = 52, /* bus=pci.0 vs bus=pci */
> >
> >
> > Exactly there're several PowerPC platforms also use pci.0 as PCI bus name.
> > $ grep -r "pci\.0"  qemu/hw/
> > qemu/hw/ppc/prep.c:    pci_bus = (PCIBus *)qdev_get_child_bus(dev,
> "pci.0");
> > qemu/hw/ppc/e500.c:    pci_bus = (PCIBus *)qdev_get_child_bus(dev,
> "pci.0");
> > qemu/hw/ppc/ppc440_bamboo.c:    pcibus = (PCIBus *)qdev_get_child_bus(dev,
> "pci.0");
> >
> > There's no much platform specific code in libvirt.
> > How can we get the exact PCI bus name and make "pci.0" work on the above
> PowerPC platforms?
> 
> As I said in my previous comments, if PPC is now using 'pci.0' as the bus
> name, this is a change from previous QEMU behaviour. If you just make
> libvirt use 'pci.0' for all PPC arches you will be breaking compatibility
> with old QEMU versions. You must therefore do proper version detection for
> this.
> 
> 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 :|
>