Re: [Qemu-devel] [RFC 0/2]: qemu-ga: drop automatic reaper

[Luiz Capitulino]

On Mon, 23 Apr 2012 09:14:18 -0500
Michael Roth <address@hidden> wrote:

> So, currently, libvirt waits indefinitely (till guest wake-up) for
> the guest-suspend-* response? I think that's broken, since
> guest-suspend-* is documented such that a response is not garaunteed,

That's true, but there's a problem on our side too.

We say that a response may not be sent, but we also don't document what clients
can do to check if the command has been successfully executed. This issue also
exists with shutdown, although it's pretty obvious that if qemu exits with a
status code of zero then it has powered down (or the user did that her/himself,
which doesn't matter). But this has to be documented to be official.

For suspend-ram and suspend-hybrid, the recommended way to know the command
has completed is to wait for the SUSPEND event and/or poll for the RunState
change (will submit a patch for this).

Now, I don't know what to do for suspend-disk. I was hoping that having a
different exit status for it was possible, but Gleb says this has problems
too as guests may "emulate" S4 by saving ram contents and then powering
down. Maybe we could use this anyway and let clients know that a regular
exit status is also possible.

However, there's another issue. This is out of qemu-ga's realm, but it's
interesting to find an unified solution: libvirt also wants to know when
the user suspends to S4 from user-space. Having a different status code
would be perfect for this...