Re: [RFC][PATCH] allow dom0 to power off machine using ACPI on shutdown.

[Harry Butterworth <harry@hebutterworth.freeserve.co.uk>]

On Thu, 2006-04-06 at 22:06 +0300, Muli Ben-Yehuda wrote:
> On Thu, Apr 06, 2006 at 07:58:50PM +0100, Harry Butterworth wrote:
> 
> > The kernel is for both dom0 and domU.  I think in the domU case the
> > hypervisor call is the correct mechanism to power off the virtual
> > machine.
> 
> I meant in the dom0 case, of course.
> 
> > > > I thought this kind of solution was better than trying to import a lot
> > > > more ACPI cruft into Xen.  Any thoughts?
> > > 
> > > I think you want kernel_power_off() here, which should do the right
> > > thing for all architectures.
> > 
> > No. kernel_power_off is currently already being called and doesn't work
> > because it calls machine_power_off which in current unstable calls the
> > hypervisor which doesn't power off the hardware.
> > 
> > My patch modifies machine_power_off to call the native pm power off if
> > present (i.e. if dom0) or the hypervisor if not (i.e. domU).
> 
> I see... Xen provides its own machine_power_off() in
> drivers/xen/core/reboot.c. If we go with dom0 shutting the machine
> down, the right fix would be to get rid of it

...can't get rid of the hypervisor call entirely because we want the
domU case to call the hypervisor to power off...

>  and / or make it call
> the arch specific machine_power_off().

...and I think it xen/core/reboot.c replaced the arch specific
machine_power_off which is no longer there to be called.

It might be better to install the hypervisor call in pm_power_off and
let it get replaced by the acpi_power_off call if ACPI is detected.
That would seem to fit in better with the way the x86 arch handles
multiple power off strategies.

I haven't looked to see how the other architectures do power off yet.

Was hoping for some comment about whether to do power off in xen or in
domU and whether the hypervisor needed notification.

-- 
Harry Butterworth <harry@hebutterworth.freeserve.co.uk>