[Qemu-devel] [RFC 0/5]: QMP: Introduce GUEST_MEDIUM_EJECT & BLOCK_MEDIUM_CHANGED

[Luiz Capitulino <lcapitulino@redhat.com>]

I've tried to implement a BLOCK_MEDIUM_EJECT event that, as we discussed[1],
would be emitted by guest-initiated ejects and by the QMP/HMP eject and change
commands.

However, that turned to be a bit problematic, because the eject and change
commands don't exactly handle tray movements: they actually insert/purge a
medium from from the drive.

Consider this example: you have a medium inserted and locked; a first eject
from HMP will tell the guest to eject the medium; if the guest does eject, a
second eject from HMP will just purge the medium (in which case
BLOCK_MEDIUM_EJECT is a bad event to be emitted).

What we really want to do is to tell mngt that the medium was purged.

The same is valid for the change command: we want to inform mngt if a medium
was inserted or purged and not emulate tray movements with two eject events
as we discussed[1].

So, the solution I came up with is to have two events:

 o GUEST_MEDIUM_EJECTED: emitted when the tray state is changed by the guest
 o BLOCK_MEDIUM_CHANGED: emitted when there's a medium change. This should
   happen when the eject and change QMP/HMP commands are used

 QMP/qmp-events.txt |   38 ++++++++++++++++++++++++++++++++++++++
 block.c            |   33 ++++++++++++++++++++++++++++++---
 block.h            |    8 ++++----
 block/raw-posix.c  |    6 +++---
 block/raw.c        |    4 ++--
 block_int.h        |    2 +-
 hw/ide/atapi.c     |    2 +-
 hw/ide/core.c      |    8 ++++----
 hw/scsi-disk.c     |    8 ++++----
 hw/virtio-blk.c    |    6 +++---
 monitor.c          |    6 ++++++
 monitor.h          |    2 ++
 12 files changed, 98 insertions(+), 25 deletions(-)