Re: -tip tree resume fail, bisect to 5bd5a45(x86: Add NX protection for kernel data)

[Lin Ming <ming.m.lin@intel.com>]

On Sat, 2010-11-27 at 01:31 +0800, mat wrote:
> Le Tue, 23 Nov 2010 23:55:27 +0100,
> mat <castet.matthieu@free.fr> a écrit :
> 
> > Le Mon, 22 Nov 2010 17:42:47 +0100,
> > Andi Kleen <andi@firstfloor.org> a écrit :
> > 
> > > > That seems to be a S3 specific code path, that won't fix anything.
> > > > Simply do:
> > > > 
> > > > echo 0 > /sys/devices/system/cpu/cpu1/online;
> > > > echo 1 > /sys/devices/system/cpu/cpu1/online;
> > > > 
> > > > and your machine will explode..
> > > 
> > > The SMP startup trampoline is copied I believe
> > > and only executed in real mode without page tables.
> > > 
> > > So it's perhaps not the trampoline, but the early startup 
> > > code that ends up being broken.
> > yes :
> > acpi wakeup code and smp trampoline are copied in low memory (first
> > 1MB).
> > 
> > So they can't end up int the kernel data mapping ?
> > 
> > So it should something else.
> > 
> > I will try to investigate on this.
> > 
> Unfortunately on my laptop supporting NX, suspend to ram seems broken
> (even without this patch) and I got only one core, so I am unable to
> test it.
> 
> Does cpu suspend/resume is broken ? Or it is only S3 ?
> 
> If yes, are there any interesting trace if we suspend only one core with
> sysfs.

echo 0 > /sys/devices/system/cpu/cpu1/online;
echo 1 > /sys/devices/system/cpu/cpu1/online;

then machine just reboots...

> 
> Thanks,
> 
> Matthieu