Re: Re: [PATCH] swsusp: do not use pm_ops (was: Re: suspend2 merge (was: Re: CFS and suspend2: hang in atomic copy))

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Monday, 7 May 2007 00:01, Alan Stern wrote:
> On Sun, 6 May 2007, Rafael J. Wysocki wrote:
> 
> > > > I think we may need yet another callback, executed before pre_snapshot()
> > > > and before we shrink memory during the hibernation, to be used by drivers
> > > > that need a lot of additional memory in pre_snapshot().
> > > 
> > > 	pre_snapshot_early()
> > 
> > OK
> 
> I changed my mind -- pre_hibernate() seems like a better name.

OK

> There could be a matching post_hibernate(), if anyone finds it necessary.  I
> considered pre_freeze(), but that's not such a good choice since the
> freezer can be used for other things in addition to hibernation.

Agreed.

> > So, I think the hibernation code ordering should be like this (let's forget
> > about ACPI for now):
> > 
> > 1) tasks are frozen
> > 2) pre_snapshot_early()
> 
> Or rather: 2) pre_hibernate()

OK

> > 3) memory is freed for the snapshot image
> > 4) pre_snapshod()
> > 5) nonboot CPUs are offlined
> > 6) IRQs are disabled
> > 7) pre_snapshot_late()
> > 8) sysdev_pre_snapshot()
> > 9) snapshot image is created
> > 10) sysdev_post_snapshot()
> > 11) post_snapshot_early()
> > 12) IRQs are enabled
> > 13) nonboot CPUs are enabled
> > 14) post_snapshot()
> > 15) snapshot image is saved
> > 16) device_shutdown()
> > 17) system is powered off
> > 
> > Apart from this, we may need notifiers for subsystems that should do something
> > before the freezing and after the thawing of tasks (like FUSE etc.).
> 
> Quite so.
> 
> > Also, if there's an error, we have to be able to thaw tasks after
> > post_snapshot() and continue running.
> > 
> > The restore code, IMO, should be like this (again, let's ignore ACPI for now):
> > 
> > 1) boot kernel is started, initrd is loaded etc.
> > 2) tasks are frozen
> > 3) snapshot image is loaded
> > 4) pre_restore()
> > 5) nonboot CPUs are offlined
> > 6) IRQs are disabled
> > 7) pre_restore_late()
> > 8) sysdev_pre_restore()
> > 9) boot kernel is replaced with the 'hibernated' kernel
> > 10) sysdev_post_restore()
> > 11) post_restore_early()
> > 12) IRQs are enabled
> > 13) nonboot CPUs are enabled
> > 14) post_restore()
> > 15) tasks are thawed
> > 16) system is running
> > 
> > and we may need a notifier for subsystems that should do something after
> > tasks have been thawed.
> 
> It sounds good to me.  Now if only it were possible to get rid of those
> pesky sysdevs...

I think that will be possible over time.

Greetings,
Rafael