[Qemu-devel] [RFC PATCH 0/2] live backup vm

[Wenchao Xia]

  This patch is a scratch which enables a full live backup of VM,
actually it is equal to savevm lively. As a test it uses hmp
command migrate to trigger the action.

  The ultimate goal is providing another command to user as:
snapshotvm [with_state] [internal] [live]
which then create vm backups with a screen image(I am not sure if a
screen snapshot is supported in qemu now). This function is enabled
in VMWARE which can automatically create full vm snapshots lively
with a screen image which seems cool, so I want to introduce it
to qemu.

Limitations:
  currently only implemented "snapshotvm with_state internal live" case.
  no screen captured in the time of creating snapshots.
  no good integration with existing savevm, migration, snapshot_blkdev
code.
  no test case yet.
  hmp/qmp API not added.

  Although there are so many gaps, but I want to send these patch
first to make sure I am in the right direction, esp the implemention
of savevm lively with vmstate, to see if there is potentional problem,
such as creating snapshots takes too long? Other cases would be simpler
if this case have no major problem found. 

Wenchao Xia (2):
  live backup vm, export functions
  live backup vm, snapshots all lively

 block.c         |   21 ++++++
 block.h         |    2 +
 buffered_file.c |  106 +++++++++++++++++++++++++++
 buffered_file.h |    1 +
 migration.c     |  215 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 migration.h     |   13 ++++
 savevm.c        |   37 +++-------
 sysemu.h        |    2 +
 8 files changed, 371 insertions(+), 26 deletions(-)