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SubjectRe: [PATCH RFC] PM / Hibernate: no kernel_power_off when pm_power_off NULL
Hi!

> Reboot logic in kernel/reboot will avoid calling kernel_power_off
> when pm_power_off is null, and instead uses kernel_halt. Change
> hibernate's power_down to follow the behavior in the reboot call.
>
> Calling the notifier twice (once for SYS_POWER_OFF and again for
> SYS_HALT) causes a panic during hibernation on Kirkwood
> Openblocks A6 board.

I can't say I like this patch.

kernel_power_off should work with pm_power_off == NULL, see for
example x86.

static void native_machine_power_off(void)
{
if (pm_power_off) {
if (!reboot_force)
machine_shutdown();
pm_power_off();
}
/* A fallback in case there is no PM info available */
tboot_shutdown(TB_SHUTDOWN_HALT);
}

. arch/arm/process.c implementation is strange:

void machine_halt(void)
{
local_irq_disable();
smp_send_stop();

local_irq_disable();
while (1);
}

## Why second disable?

/*
* Power-off simply requires that the secondary CPUs stop performing
any
* activity (executing tasks, handling interrupts). smp_send_stop()
* achieves this. When the system power is turned off, it will take
all CPUs
* with it.
*/
void machine_power_off(void)
{
local_irq_disable();
smp_send_stop();

if (pm_power_off)
pm_power_off();
}

## It really should do while (1) here.

Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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