ACPI was RE: [Techtalk] NFS

Akkana akkana at
Thu Feb 6 20:58:53 EST 2003

Nielson, Bert writes:
(BTW, your messages would be easier to reply to if you set your mailer
to wrap at a standard line length, like 72 ...)

> I would love to find additional information about ACPI and how to use
> it.  The most important information I would like to find is how to
> suspend my laptop to disk.

I believe suspend-to-disk is the "software suspend" that is being
worked on in the 2.5 kernel.  Search for that phrase in the linux
kernel mailing list archives for more information on the current
status, but my impression is that they're making good progress.
At one time there were backports to 2.2 and 2.4 kernels, but I
don't know whether there's a current backport (please report back
if you find one).

As far as suspend-to-ram, most laptops offer two options for suspending:
APM and ACPI.  I don't believe ACPI suspend works yet in linux (so
newer ACPI-only laptops may be out of luck :-( ); APM suspend works
on some machines but not others (on every machine I've tried it on,
apm -s and apm -S both work, but usually hang the machine on resume,
either while talking to the network card or the video card).
I'm not sure if ACPI suspend works on any linux machine yet.

On my Vaio I'm lucky: the power button apparently causes a BIOS-driven
suspend, so I don't need APM or ACPI (though there are kernel options
which somehow disable the BIOS suspend).  But it eats power faster than
I like, so I'm definitely looking forward to future kernels with
software suspend-to-disk.

MobiliX has a good page on laptop power issues:


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