This patch series 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-...
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.
The existing pc-1.0 machine type is renamed to pc-1.0-qemu-git,
with pc-1.0 becoming an alias for one or another, as selected
by a configure option (defaulting to pc-1.0-qemu-git, IE no
change).
Two aproaches are taken:
* In hw/timer/i8254_common.c, the VMSTATE_UINT32_TEST macro
is used to test the version for the irq_disable flags,
allowing version 3 or more, or version 2 for an inbound
migrate from qemu-kvm (only).
* In hw/acpi/piix4.c, qemu-kvm incorrectly uses version 2 for
a version 3 structure, causing acpi_load_old to be used.
acpi_load_old detects this situation based on the machine type
and restarts the attempt to load the vmstate using a
customised VMStateDescription. The above cleaner approach is
unavailable here.
I developed this on qemu 2.0 but have forward ported it (trivially)
to master. My testing has been on a VM live-migrated-to-file from
Ubuntu Precise qemu-kvm 1.0.
I have given this a moderate degree of testing but it could do
with more.
Note that certain hardware devices (including QXL) will not
migrate properly due to a fundamental difference in their internal
state between versions.
Also note that (as expected) migration from qemu-2.x to qemu-1.0
will not work, even if the machine types are the same.
Alex Bligh (2):
Add machine type pc-1.0-qemu-kvm for live migrate compatibility with
qemu-kvm
Add configure option --enable-pc-1-0-qemu-kvm
configure | 12 ++++++++++++
hw/acpi/piix4.c | 47 +++++++++++++++++++++++++++++++++++++++++++++--
hw/i386/pc_piix.c | 38 +++++++++++++++++++++++++++++++++++++-
hw/timer/i8254_common.c | 10 +++++++++-
4 files changed, 103 insertions(+), 4 deletions(-)
--
1.7.9.5