Can I xc_await_suspend() for a suspend event caused by another application?

[Razvan Cojocaru <rcojocaru@bitdefender.com>]

Hello,

I've noticed that the xc_suspend_evtchn_init() functions in xenguest.h
connect the client application to a guest suspend event channel, and
that it's possible to subscribe to these events, in theory even if you
never signal the channel (i.e. even if you don't issue a suspend request).

But all the in-tree examples I've read seem to first signal the channel
and then wait on the same channel for the confirmation that the guest is
suspending.

Can the event channel be used solely to inform a monitoring application
that _another_ application (for example, xl) has requested a suspend?

To give you some context, I'm interested in being able to make the
difference between the case when a guest is going into suspend mode (and
is still running), and the case when a guest is history (which I'm now
doing via @releaseDomain xenstore events). Basically, the difference
between a regular guest shutdown and what happens on "xl save" (as early
as possible, while the guest is still running).


Thanks,
Razvan