Re: [RFC][PATCH 1/3] Hibernation: Enter platform hibernation state in a consisten way (rev. 2)

[Pavel Machek <pavel@ucw.cz>]

Hi!

> Make hibernation_platform_enter() execute the enter-a-sleep-state sequence
> instead of the mixed shutdown-with-entering-S4 thing.
> 
> Replace the shutting down of devices done by kernel_shutdown_prepare(), before
> entering the ACPI S4 sleep state, with suspending them and the shutting down of
> sysdevs with calling device_power_down(PMSG_SUSPEND) (just like before entering
> S1 or S3, but the target state is now S4).  Also, disable the nonboot CPUs
> before entering the sleep state (S4), which generally always is a good idea.
> 
> This is known to fix the "double disk spin down during hibernation" on some
> machines, eg. HPC nx6325 (ref. http://lkml.org/lkml/2007/8/7/316 and the
> following thread).  It also generally causes the hibernation state (ACPI S4) to
> be entered faster.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> ---
>  kernel/power/disk.c |   55 ++++++++++++++++++++++++++++++++++++++--------------
>  1 file changed, 41 insertions(+), 14 deletions(-)
> 

> +	local_irq_disable();
> +	error = device_power_down(PMSG_SUSPEND);
> +	if (!error) {
> +		error = hibernation_ops->enter();
> +		/* We should never get here */

Are you sure it is good idea to enable interrupts/power up devices
when this happens? AFAICT image is already on disk an intact at this
point, safe thing to do is while(1);...
									Pavel
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