Re: Problems with SMP & ACPI powering off

[Mark Lord <lkml@rtr.ca>]

Rafael J. Wysocki wrote:
> On Friday, 28 September 2007 15:22, Mark Lord wrote:
> > Rafael J. Wysocki wrote:
> > > On Friday, 28 September 2007 06:57, Len Brown wrote:
> > > > On Thursday 27 September 2007 18:00, Rafael J. Wysocki wrote:
> > > > > On Thursday, 27 September 2007 23:29, Mark Lord wrote:
> > > > > > Question:  do we disable all CPUs except 0 when doing ACPI power off?
> > > > > No, but we should.
> > > > We used to.
> > > > It is absolutely mandatory -- else it confuses the BIOS on some boards
> > > > b/c it isn't expecting SMM to get entered from other than cpu0.
> > > Can we use the CPU hotplug for that, like in the suspend/hibernation case?
> > Well, so far it's working:  about ten poweroffs since I patched it,
> > and no issues with any of them.  Prior to that, it seemed like about
> > one in five poweroffs wouldn't (power off).
> >
> > It'll take a lot more testing to confirm, though.
> >
> > What can I call to determine if more than one CPU is enabled, anyway?
> >
> > Here's the hack I'm using here, very situation (2 cores) specific,
> > and it still has some printk's leftover with a sleep so I have time
> > to read them before the lights go out.  :)
>
> Well, we have disable_nonboot_cpus() that we use for suspend and that is
> supposed to be general.
>
> The question is when to call it.

How about from the obvious candidate: kernel/sys.c::kernel_power_off() ?

I'll rework my hack into a proper patch there,
repost it here, and test with it for another day or two.

-ml
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