[libvirt] [PATCH 7/7] qemu: Support newer ivshmem and prefer that over the legacy one

[Daniel P. Berrange]

On Wed, Aug 10, 2016 at 01:50:11PM +0200, Martin Kletzander wrote:
> QEMU added support for ivshmem-plain and ivshmem-doorbell.  Those are
> reworked varians of legacy ivshmem that are compatible, but have sane
> specification and handling.
> 
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1347049
> 
> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
> ---
>  src/qemu/qemu_command.c                            | 66 ++++++++++++++++++++--
>  .../qemuxml2argv-shmem-plain-doorbell.args         | 42 ++++++++++++++
>  .../qemuxml2argv-shmem-plain-doorbell.xml          | 54 ++++++++++++++++++
>  tests/qemuxml2argvtest.c                           |  3 +
>  4 files changed, 161 insertions(+), 4 deletions(-)
>  create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-shmem-plain-doorbell.args
>  create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-shmem-plain-doorbell.xml

Isn't this going to break migration compatibility. eg if someone
has a guest running on a QEMU with ivshmem, which also has the
ivshmem-plain, then when they upgrade libvirt their guest will
guest the different device, which has different migration ABI ?

Or is there a blocker that entirely prevents migration with
ivshmem, making it a non-issue ?

Regards,
Daniel
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