Re: [PATCH] Add MCE resume under ia32

[Shaohua Li <shaohua.li@intel.com>]

On Wed, 2005-08-24 at 05:59 +0200, Andi Kleen wrote:
> [adding discuss to cc]
> 
> On Wednesday 24 August 2005 05:47, Shaohua Li wrote:
> > On Wed, 2005-08-24 at 05:12 +0200, Andi Kleen wrote:
> > > On Wednesday 24 August 2005 03:59, Shaohua Li wrote:
> > > > On Wed, 2005-08-24 at 03:52 +0200, Andi Kleen wrote:
> > > > > Shaohua Li <shaohua.li@intel.com> writes:
> > > > > > x86-64 has resume support. It uses 'on_each_cpu' in resume method,
> > > > > > which is known broken. We'd better fix it.
> > > > >
> > > > > What is broken with it?
> > > >
> > > > It's a sysdev. The resume method is invoked with interrupt disabled.
> > >
> > > But only local interrupt disabled, no?
> > >
> > > Hmm - didn't we have a WARN_ON(irqs_disabled()) in smp_call_function().
> > >
> > > Anyways, it'll probably still work for now because the system should
> > > be synchronized at this point.
> >
> > We are using cpu hotplug framework for MP suspend/resume. When sysdev's
> > resume is calling, APs actually aren't up. So it actually can't work.
> 
> Ok, that's a new problem.
> 
> There were recently some patches to add individual MCE entries
> for each CPU to sysfs. They are only used for set up right now,
> but perhaps they can be linked somehow to the cpu sysfs devices
> and get suspend/resume events from there.
The boot code already initialized MCE for APs, it isn't required to
initialize again. The MCE entries are cpuhotplug friendly, so for
suspend/resume.

Thanks,
Shaohua