Re: [linux-pm] [PATCH] hibernation should work ok with memory hotplug

Pavel Machek
2008-11-06T08:47:27Z

Hi!

> > To trigger "2", the user have special console to tell firmware "enable this memory".
> > Such firmware console or users have to know "the system works well." And, more important,
> > when the system is suspended, the firmware can't do hotplug because the kernel is sleeping.
> > So, such firmware console or operator have to know the system status.
> >
> > Am I missing some ? Current linux can know PCI/USB hotplug while the
> > system is suspended ?
>
> * echo 'disk' > /sys/power/state
> * count number of pages to write to disk
> * turn all interrupts off
> * copy pages to disk
> * power down
>
> I think the race we're trying to close is the one between when we count
> pages and when we turn interrupts off. I assume that there is a reason
> that we don't do the *entire* hibernation process with interrupts off,
> probably because it would "lock" the system up for too long, and can
> even possibly fail.

We need interrupts to write pages to the disk.
Pavel
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