Re: Why do so many machines need "noapic"?

From: Dave Jones
Date: Mon Sep 24 2007 - 17:32:57 EST

On Sat, Sep 15, 2007 at 01:08:25PM +0100, Matthew Garrett wrote:
> On Sat, Sep 15, 2007 at 04:08:02AM -0700, Andrew Morton wrote:
> > I believe that about two years ago we broke something which caused quite a
> > large number of people to need noapic. Is that the case with any of your
> > machines? Do you know if they run 2.6.ancient without noapic?
> My recollection is that we shifted from "Enable the apic even if the
> BIOS disabled it" to "Only use the apic if the BIOS didn't disable it"
> around that time, which meant that distributions could actually turn on
> apic-on-up support without breaking everything. That might correspond to
> what you're seeing.

If memory serves correctly, that was circa 2.6.10, back in these commits..

commit a068ea13d1db406e15c346e93530343f6e70184c
Author: Len Brown <len.brown@xxxxxxxxx>
Date: Sun Oct 10 05:21:08 2004 -0400

[ACPI] If BIOS disabled the LAPIC, believe it by default.
"lapic" is available to force enabling the LAPIC
in the event you know more than your BIOS vendor.

commit 2fcfece90db9643b6f30a7ad343898a2871e6a81
Author: Len Brown <len.brown@xxxxxxxxx>
Date: Sat Oct 9 20:12:45 2004 -0400

[ACPI] Don't enable LAPIC when the BIOS disabled it.
Doing so apparently breaks every Dell on Earth.

But those changes relate to the local APIC, which 'noapic' shouldn't
have any effect on should it ?


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