[Qemu-devel] wake-on-lan & IPMI implementation; real power-off and -no-shutdown

["François Revol" <revol@free.fr>]

Hello,
while working on a demonstrator for a green-IT project, to show
scheduled machine shutdown and powering depending on various
conditions, I wondered if I could use QEMU with wake-on-lan
transparently, but it seems it's not implemented at all.

I though I could try to add support for it, and with -S it theorically
should be doable at least for the first boot, but the network packets
do not go much further until the NIC is actually initialized, as most
network layers use qemu_can_send_packet() which returns 0 if the
machine is stopped.
Hacking this function to return 1 seems to push the packet upward, but
I couldn't find a single point where I could check for WOL packets,
different -net subsystems using different code paths.

Also, it seems -no-shutdown doesn't actually "stop the emulation" as
said in the manual, it actually keeps the vm running (and using cpu),
despite the OS trying to shutdown via ACPI. At least I tested so with
Haiku (and acpi=true in kernel config), which properly exits QEMU
without -no-shutdown.

Ideally this would evolve into supporting IPMI, which would allow
managing VMs exactly like physical servers without concern, appart
launching the actual process first.
cf.
http://en.wikipedia.org/wiki/Intelligent_Platform_Management_Interface
http://openipmi.sourceforge.net/

Anyone interested in this ?
Anyone tried already ?

François.