Bug 4763

Distribution: Gentoo Linux (Vanilla Kernel)

Hardware Environment:
Architecture: X86
Name: Clevo 5600D 
CPU: Pentium4 2.8 GHz, 533MHz FSB
This is a Laptop I bought in December 2002.
It was sold under many brands like Sager/Eurocom/Alienware/Promedion 56XX and
888X, Alienware m51, Littlebit 64X)

Software Environment:
not really relevant here, I think.


Problem Description:

Somewhere in February/March 2004 I first tried to build a kernel with working
ACPI support.
The standard kernel, freezed at startup when ACPI was enabled.
I then used the acpi-20040211-2.4.25.diff patch and I got a working kernel with
ACPI working perfectly.

In November/December 2004 I tried first to upgrade to 2.6 (2.6.9 maybe), both
unpatched and patched with the newest ACPI patches led to a system freeze during
system boot.
I also tried the same with a 2.4 kernel which gave me the same results.
As I hadn't too much time back then, I just used the old patch again, which
still worked on a gentoo-sources-2.4.25 (instead of a vanilla kernel).

Now I have some time and I'd like to solve problem finally:

The first what I did, was downloading one of the latests vanilla kernels
(2.6.11.11) through portage (gentoo package management tool).

I still freezed on startup (except if I passed the kernel parameter acpi=off).

I changed the kernel config to turn as many options as possible into modules.
So I got the modules ac.ko, button.ko, battery.ko, processor.ko and thermal.ko.

Booting the system worked fine now, including ACPI support.
Then I inserted one module after the other. First ac, then button, then battery
and all worked well until here (I tested them all over the /proc interface, they
all worked like in my previous kernel, I also found no suspicous lines in the
syslog (most useful kernel and all ACPI debugging options were compiled in))

When I inserted the processor.ko module the system freezed instantly (before I
could type any further characters on the terminal, but a new shell prompt was
there).


Steps to reproduce:
1. Boot up system with processor acpi support compiled into a module
2. load processor.ko module
3. System has freezed instantly.


As it seems to me. The problem in the acpi cpu code, that makes my laptop
freeze, was very likely introduced sometime in 2004.

I have good experience in C (and also C++), but none in kernel programming. So I
 would look at the source if you could give me some hints where the problem most
likely could be found (and maybe where I could find some general kernel
debugging tips).

Thank you for any help.