Re: [PATCH 14/21] i386 Apm is on cpu zero only

From: Alan Cox
Date: Tue Nov 08 2005 - 08:24:25 EST


On Maw, 2005-11-08 at 04:53 -0800, Zachary Amsden wrote:
> Can't hurt, and APM is largely obsolete because of ACPI, so I'm only
> concerned with trimming and keeping adequate protection of the kernel
> from APM code while maintaining correctness. I don't have a nice set of
> old machines with enough wacky APM BIOSen to validate that unpinning the
> CPU is ok.

A large number of SMP machines, probably the majority of APM based ones
require that APM calls occur on CPU#0. As I understand it from a BIOS
engineer involved in debugging that problem Redmond always does APM from
CPU #0 and may even guarantee it.

Alan

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