From: Marc-Christian Petersen <m.c.p@wolk-project.de>
Organization: Working Overloaded Linux Kernel
To: Mikael Pettersson <mikpe@csd.uu.se>, Dave Jones <davej@codemonkey.org.uk>
Subject: Re: [PATCH][2.4.22-rc2] Disable APIC on reboot.
Date: Fri, 15 Aug 2003 21:22:10 +0200
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On Tuesday 12 August 2003 01:33, Mikael Pettersson wrote:

Hi Mikael,

> disable_local_APIC() now checks if detect_init_APIC() enabled the
> local APIC via the APIC_BASE MSR, and if so it now disables APIC_BASE.
> Previously we would leave APIC_BASE enabled, and that made some
> BIOSen unhappy.
> The SMP reboot code calls disable_local_APIC(). On SMP HW there is
> no change since detect_init_APIC() isn't called and APIC_BASE isn't
> enabled by us. An SMP kernel on UP HW behaves just like an UP_APIC
> kernel, so it disables APIC_BASE if we enabled it at boot.
> The UP_APIC disable-before-suspend code is simplified since the existing
> code to disable APIC_BASE is moved into disable_local_APIC().
> (Felix K?hling originally reported the BIOS reboot problem. This is a
> fixed-up version of his preliminary patch.)

please correct me if I say something really stupid now but shouldn't the APIC 
be disabled only during reboot time and enabled again at a new boot?

my experience with this patch is, after a reboot he APIC isn't enabled again 
until I power off my machine.

ciao, Marc

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