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

[Anthony Liguori <anthony@codemonkey.ws>]

On 03/15/2010 10:55 AM, Daniel P. Berrange wrote:
> On Mon, Mar 15, 2010 at 04:01:27PM +0100, Fran?ois Revol wrote:
>    
>> 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.
>>      
> Hmm, I think -no-shutdown should at least stop the CPUs executing. It is
> not really useful on its own though. The app managing QEMU would want to
> use the new JSON based monitor to listen for the SHUTDOWN event to be
> emitted, so it can detect the shutdown completing&  then take action it
> wants either reset the guest, or kill QEMU, etc
>    

The semantics of -no-shutdown are awful.

I'd personally prefer to see the option deprecated and a new set of 
options introduced with clearer semantics.

Currently, -no-shutdown does too many things.  It affects reboot 
behaviour, shutdown behaviour, the behavior of the SDL close button.  
Each of these things should be individual tunables.

Regards,

Anthony Liguori

> Daniel
>