[libvirt] [PATCH 2/4] backup: Add two new qemu capabilities

[Eric Blake]

On 6/6/19 7:51 AM, Peter Krempa wrote:
> On Wed, Jun 05, 2019 at 22:01:08 -0500, Eric Blake wrote:
>> Add two capabilities for testing features required for the upcoming
>> virDomainBackupBegin: use block-dirty-bitmap-merge as the generic
>> witness of bitmap support needed for checkpoints (since all of the
>> bitmap management functionalities were finalized in the same qemu 4.0
>> release), and the bitmap parameter to nbd-server-add for pull-mode
>> backup support.  Even though both capabilities are likely to be
>> present or absent together (that is, it is unlikely to encounter a
>> qemu that backports only one of the two), it still makes sense to keep
>> two capabilities as the two uses are orthogonal (full backups don't
>> require checkpoints, push mode backups don't require NBD bitmap
>> support, and checkpoints can be used for more than just incremental
>> backups).
>>
>> Signed-off-by: Eric Blake <eblake at redhat.com>
>> ---
>>  src/qemu/qemu_capabilities.h                      | 4 ++++
>>  src/qemu/qemu_capabilities.c                      | 6 ++++++
>>  tests/qemucapabilitiesdata/caps_4.0.0.aarch64.xml | 2 ++
>>  tests/qemucapabilitiesdata/caps_4.0.0.ppc64.xml   | 2 ++
>>  tests/qemucapabilitiesdata/caps_4.0.0.riscv32.xml | 2 ++
>>  tests/qemucapabilitiesdata/caps_4.0.0.riscv64.xml | 2 ++
>>  tests/qemucapabilitiesdata/caps_4.0.0.s390x.xml   | 2 ++
>>  tests/qemucapabilitiesdata/caps_4.0.0.x86_64.xml  | 2 ++
>>  8 files changed, 22 insertions(+)
> 
> So the code looks good to me, but we need to clarify one thing before
> ACK.
> 
> Is there anything that would change libvirt's behaviour incompatibly if
> these are specified? In some cases these also imply a libvirt behaviour
> change (e.g. different command line) and thus not pushing those in the
> same release as the implementation might cause problems.

So far, the only things that depend on the capabilities are the new code
additions for checkpoints and pull-mode backups; existing libvirt.git
should have no change in behavior whether or not the capabilities are
detected.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: OpenPGP digital signature
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20190606/a10c02ca/attachment-0001.sig>