Re: PROBLEM: APIC on a Pentium Classic SMP, kernel 2.4.21-pre5 to 2.4.23-pre3

From: Maciej W. Rozycki
Date: Mon Sep 08 2003 - 10:08:24 EST


On Mon, 8 Sep 2003, Mikael Pettersson wrote:

> >IRQ problems with APIC enabled on a Neptune chipset, Pentium 90 SMP.
> >
> >Description
> >
> >Since kernel 2.4.21-pre2, IRQ problems are present on my Pentium 90 SMP, wi=
> >th
> >APIC enabled. It works well with 2.4.20 with APIC enabled, or with newer
> >kernels with "noapic" kernel option.
>
> There were a lot of I/O-APIC & MP table parsing changes in 2.4.21
> for clustered apic. Chances are something there broke on your
> ancient BIOS & mobo. I can't immediately see anything obviously
> broken in 2.4.21: you'll have to identify the first pre-patch where
> things broke and then test or revert it piece by piece.

The log shows the system is using a default MP configuration (i.e. no MP
table, only a suitable header). The recent changes definitely broke such
systems -- someone doing them seems to have not cared about the default
configurations. I've noticed the breakage recently and put it on my to-do
list, but unfortunately I have no time to code a fix now.

--
+ Maciej W. Rozycki, Technical University of Gdansk, Poland +
+--------------------------------------------------------------+
+ e-mail: macro@xxxxxxxxxxxxx, PGP key available +

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