Re: Suspend ops on x86 architectures.

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

Hi,

On Sunday, 18 of November 2007, Francis Moreau wrote:
> Hello,
> 
> I'm trying to get an idea on how suspend works on Linux. I already looked at
> Documentation/power, but I'm clueless about x86 architectures. They don't
> seem to define any suspend ops.

Yes, they do, via ACPI.  Please see drivers/acpi/sleep/main.c .

> Can anyone give me some pointers or some hints, I'd like to look at the
> low level part of the suspend on these architectures also I'd like to know
> what kind of events wake up the system once it's suspended. I guess
> interrupts are used but which ones exactly.

This also is controlled by ACPI.  The ACPI platform firmware handles the
wake-up events and transfers control to the kernel by jumping to an address
specified before the suspend.

> Also I'm wondering how jiffies or system clock are updated correctly after
> resuming.

AFAICS, we use the pre-suspend value of jiffies.  The generic clocksource
timekeeping is handled by timekeeping_resume() in kernel/time/timekeeping.c .

Greetings,
Rafael