Re: apm system does not power off anymore

[Andrew Morton]

On Mon, 15 Oct 2007 16:37:20 +1000 Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:

> On Sun, 14 Oct 2007 23:23:16 -0700 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > Also, it's bad that the operator has to provide some special boot command-line
> > option to make the machine work properly.  Please consider this to be a
> > bug.  Has it always needed apm=power-off?
> 
> It has always been that way because the behaviour of APM on SMP is not
> defined.  We discovered early that it will work (at least for powering
> off) for most SMP machines as long as the APM calls are done on CPU 0.
> However on an SMP machine that does not cope, very bad things happen -
> thus the operator has to explictly enable the power off behaviour on an
> SMP box.  (On UP power off is enabled by default.)

hrm, OK.

But it could have been controlled by a more-user-friendly runtime knob, I
guess.  Not that it's worth changing that now.

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