On 06/06/07, Thomas Renninger <trenn@xxxxxxx> wrote:
Hi,
I made up a little How-To for what I find out is nice to debug ACPI
problems.
Nice :-)
Any enhancements, corrections, etc. are very much appreciated.
See below.
I'd like to have a final version in the Documentation section.
When you send in the patch to add that final version, please also
remember to add an entry to Documentation/00-INDEX
[snip]
How to debug ACPI Problems
==========================
Thomas Renninger <trenn@xxxxxxx>, 2007
Copyright (C) 2007 SUSE Linux GmbH
1. Introduction
---------------
1.1. General Info
- - - - - - - -
Perhaps start out here by telling people what ACPI is. Something like this:
ACPI stands for Advanced Configuration and Power Interface.
Please refer to the latest ACPI spec for general ACPI information:
http://www.acpi.info/spec.htm
ACPI is required by most recent x86, x86_64 and IA64 architecture based
machines.
In general ACPI tables provide information from the BIOS to the OS.
There are ACPI tables (DSDT and SSDTs), written in the ACPI Source
Language (ASL) which include byte code (similar to Java byte code) that gets
interpreted by the OS. The kernel makes use of provided BIOS functions
The word "provided" seems superfluous here.
[snip]
The ACPI tables of your system can be extracted with the acpidump tool:
I think the colon ":" at the end of this line should be removed.
in the latest pmutils package from here:
ftp://ftp.kernel.org/pub/linux/kernel/people/lenb/acpi/utils
[snip]
In history people used to override their DSDT to workaround BIOS or even kernel
I would replace "In history people used to ..." with "Historically
people used to ...".
[snip]
If you expect the bug in a module in drivers/acpi/*.c code you might have luck
and be able to find or narrow down the culprit by simple printks.
I would rewrite that bit as :
If you suspect the bug to be in a module in drivers/acpi/*.c code, you
may be able to find or narrow down the culprit simply by adding
printk()'s.
On more complicated bugs you should make use of the ACPI_DEBUG=y facility.
Maybe just me, but I would say "For" here instead of "On".
[snip]
Note: In kernel versions before 2.6.22 the boot parameters are:
should be "...the boot parameters were:" - past tense.
[snip]
interface (Documentation/networking/netconsole.txt) to write away
syslog messages over network or firescope
"... to write away syslog messages over network ..." sounds a little
clumsy to me. Why not simply write "... to send syslog messages over
network ..." ?
(patches already exist in
2.6.22-rcX-mm?) to send syslog messages over firewire.
The latter might be the only way to debug early hangs on laptops
without serial console anyway.
"without a serial console" ???
3.2.2 Using ACPI_DEBUG Boot Parameters via /sysfs and /proc
The same as 3.2.1., you can also pass the parameters at runtime e.g.
via:
echo 0x1F >/proc/acpi/debug_level # before 2.6.22 or
echo ?!? >/sys/?/!/? # Rui?
Seems like some bits are missing here ^^^
Wrapping such statements around loading and unloading a bug affected
ACPI module might give you the possibility to increase debug_level,
but still only give you a managable amount of debug output.
s/managable/manageable/
[snip]
--
Jesper Juhl <jesper.juhl@xxxxxxxxx>
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please http://www.expita.com/nomime.html
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