[libvirt] [Qemu-devel] [PATCH] [RFC] Add machine type pc-1.0-qemu-kvm for live migrate compatibility with qemu-kvm

[Andreas Färber]

Hi Alex,

+ quintela, mst, libvirt

Am 22.07.2014 20:43, schrieb Alex Bligh:
> Add a machine type pc-1.0-qemu-kvm for live migrate compatibility
> with qemu-kvm version 1.0.
> 
> Signed-off-by: Alex Bligh <alex at alex.org.uk>
> ---
>  hw/acpi/piix4.c          |   49 ++++++++++++++++++++++++++++++++++++++++++++--
>  hw/i386/pc_piix.c        |   31 +++++++++++++++++++++++++++++
>  hw/timer/i8254_common.c  |   41 ++++++++++++++++++++++++++++++++++++++
>  include/hw/acpi/piix4.h  |    1 +
>  include/hw/timer/i8254.h |    2 ++
>  5 files changed, 122 insertions(+), 2 deletions(-)
> 
> This RFC patch adds inbound migrate capability from qemu-kvm version
> 1.0. The main ideas are those set out in Cole Robinson's patch here:
> http://pkgs.fedoraproject.org/cgit/qemu.git/tree/0001-Fix-migration-from-qemu-kvm.patch?h=f20
> however, rather than patching statically (and breaking inbound
> migration on existing machine types), I have added a new machine
> type (pc-1.0-qemu-kvm) without affecting any other machine types.

This sounds like a really cool feature that SUSE would probably be
interested in extending back to 0.14 and 0.15, but I see a fundamental
flaw: libvirt on those old source systems does not know it should use a
different machine name on the destination side and would still use
pc-1.0, wouldn't it? After all, it needs to be able to migrate to other
old qemu-kvm machines, so it can't just be updated to use the new name.

Minor bikeshedding: I would ask to keep the package name in front of the
machine version, e.g. qemu-kvm-pc-1.0. Or just kvm-pc-1.0 since this is
a QEMU parameter anyway.

Haven't reviewed the code in detail yet.

Regards,
Andreas

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