Re: [libvirt] [PATCH RFC 0/4] Allow hibernation on guests

> One thing, that you'll probably notice is this > 'set-support-level' command. Basically, it tells GA what qemu version > is it running on. Ideally, this should be done as soon as > GA starts up. However, that cannot be determined from outside > world as GA doesn't emit any events yet. > Ideally^2 this command should be left out as it should be qemu > who tells its own agent this kind of information. > Anyway, I was going to call this command in qemuProcess{Startup, > Reconnect,Attach}, but it won't work. We need to un-pause guest CPUs > so guest can boot and start GA, but that implies returning from qemuProcess*. > > So I am setting this just before 'guest-suspend' command, as > there is one more thing about GA. It is unable to remember anything > upon its restart (GA process). Which has BTW show flaw > in our current code with FS freeze & thaw. If we freeze guest > FS, and somebody restart GA, the simple FS Thaw will not succeed as > GA thinks FS are not frozen. But that's a different cup of tea. > > Because of what written above, we need to call set-level > on every suspend. IMHO all this says that the 'set-level' command is a conceptually unfixably broken design & should be killed in QEMU before it turns into an even bigger mess. Once we're in a situation where we need to call 'set-level' prior to every single invocation, you might as well just allow the QEMU version number to be passed in directly as an arg to the command you are running directly thus avoiding this horrificness.