Easy inspection of ACPI AML opcodes w/o need for CONFIG_ACPI_DEBUG and the ACPI debug tweaks.

[Colin Ian King]

Hi there,

I've written a SystemTap script that allows one to trace the execution
of the ACPI AML code without the need to build a kernel with
CONFIG_ACPI_DEBUG and do all that messy debug_level and debug_layer
configuration to get the correct kind of debug out of the kernel.

The script is in my pmdebug git repo:

http://kernel.ubuntu.com/git?p=cking/pmdebug.git;a=blob;f=systemtap/amltrace/amltrace.stp;h=80f9915a1bc4e022021823748c31d3510cda4a56;hb=279d2852ad5336e7bb667cde3cad71856d23c2cc

To run, install systemtap and a relevant kernel .ddeb (do you need to
reboot after installing this?)

Then download the script and run with:

sudo ./stap -g  

and wait for the "Starting ACPI debugger." message

If you exercise AML code (e.g. hit volume keys) the opcodes are dumped
to your terminal in real-time.   Apart from being a handy tool for
debugging AML issues, it's a neat demo of what can be done with
SystemTap.

Caveat: This has been tested on Oneiric. You mileage may vary.

Oh, and if you want to see the AML code from your firmware, you can dump
this quite easily using:

sudo fwts --disassemble-aml


Colin