[libvirt] [RFC v3 PATCH 0/5] PowerPC : Extend libvirt for the PowerPC-KVM platform

Prerna Saxena prerna at linux.vnet.ibm.com
Tue Nov 29 14:55:25 UTC 2011


Recent development in KVM for 64-bit Power ISA Book3S machines, allows
users to run multiple KVM guest instances on POWER7 and PPC970
processor based systems.  Also qemu-system-ppc64 has been enhanced to
support a new machine type "pseries" suitable for Power Book3S machines.
This addition effectively brings the KVM+qemu combination to run
multiple guest instances on a Power Book3S machine.

Libvirt continues to be the key interface to configure and manage the
KVM guest instances on x86.  This patch set is an effort to enable
libvirt to support KVM guest configuration and management on Power Book3S
machines.

Based on community discussion around the earlier version, this patch
series augments the present 'kvm' driver to support PowerPC-KVM based
guests.Since some of the supported devices vary between architectures,
libvirt must be capable of choosing supported device backends and
defaults for each architecture in qemu.

To check if qemu supports a certain feature, libvirt at present parses
the -help string which is generated by running the qemu binary with the
'-h' argument. This approach is gated by QEMU's inherent limitation. 
When generating the list of allowed options with the '-h' flags, qemu
today blindly lists all options defined for any architecture/platform
instead of doing any arch-specific checking. This tricks libvirt into
assuming a much bigger set of host capabilities than is actually
available.
Ideally, it would be good to have qemu specify a list of devices for a
given architecture and platform which libvirt can parse to understand 
supported capabilities for that guest.

As a part of this patchset, there is an attempt to cleanly bifurcate
libvirt code and to remove x86-specific assumptions from generic qemu
commandline code.

Series Description:
-------------------
This patch series consists of 5 patches :
Patch 1/5 : Use sysfs to gather host topology in place of /proc/cpuinfo.
Patch 2/5 : Add PowerPC CPU Driver
Patch 3/5 : Add support for qemu-system-ppc64
Patch 4/5 : Clean up x86-specific assumptions from generic qemu code.
Patch 5/5 : Add address family "spapr-vio"

Changelog:
---------
** v1->v2 :
* Patches 1,2,3 unchanged ; The hacks in Patch 4 of v1 replaced by a
  new patch to neatly select arch-specific features.

** v2->v3 :
* Patches 1,2,3 have minor cleanups ; Patch 4 no longer has an
  arch-specific handler routine. It is now replaced by a much simpler
  patch that merely removes x86/pc-specific assumptions from libvirt.

** v3->v4 :
* Patches 1,2,3,4 unchanged ; patch 5 is a new addition from Michael Ellerman
  that adds a new device-tree based addressing mechanism for the 'pseries'
  guest.


-- 
Prerna Saxena

Linux Technology Centre,
IBM Systems and Technology Lab,
Bangalore, India




More information about the libvir-list mailing list