Re: apm broken - again (2.1.122) + FIX

Alan Cox (alan@lxorguk.ukuu.org.uk)
Thu, 17 Sep 1998 16:11:28 +0100 (BST)


> On one sunny day, somebody disabled APM+SMP, causing kernel oopses everytime
> I try to switch of my machine (using apm). The stated reason was (I believe),
> that APM does not work with SMP. But fact is:

Correct. APM might happen to apparently work, it might even be safe for
a few machines, it might also save and restore with the L2 cache of a CPU
corrupted (which appears to occur on some boxes).

The code is right

> #ifdef __SMP__
> if (smp_num_cpus > 1) {
> printk(KERN_NOTICE "APM disabled: APM is not SMP safe.\n");
> return;
> }
> #endif
>
> with it, I get oopses, without it everything works fine. Yes, I'm not
> enabling any powersaving, I just want an automatic power-off, and the

That code is right, fix the real cause of the oops. If you want SMP power
management write an ACPI driver

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