= ACPI: Debugging AML with SystemTap =

This document is intended to explain to dump out ACPI AML opcodes at run time using SystemTap.  This approach is an alternative to dumping out AML opcodes using CONFIG_ACPI_DEBUG and setting the appropriate debug_level/debug_layer bitmasks that produces copious amounts of debug.

== Instructions ==

1. Clone the pmdebug git repository:

git clone git://kernel.ubuntu.com/cking/pmdebug.git

2. Install SystemTap and the appropriate kernel .ddebs

{{{
sudo apt-get install systemtap
}}}

2.1) Create an /etc/apt/sources.list.d/ddebs.list by running the following line at a terminal: 

{{{
echo "deb http://ddebs.ubuntu.com $(lsb_release -cs) main restricted universe multiverse" |\
 sudo tee -a /etc/apt/sources.list.d/ddebs.list
}}}

2.2) Import the debug symbol archive signing key: 

{{{
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 428D7C01
}}}

2.3) Then run:

{{{
sudo apt-get update
}}}

2.4) Download and install the debug kernel, e.g.

{{{
sudo apt-get install linux-image-`uname -r`-dbgsym
}}}

3. Run the script

sudo stap -g pmdebug/systemtap/amltrace/amltrace.stp

..this will take a few moments to build and then run.  You can then see the objects being evaluated, an AML op-code disassembly and calls to other methods as the AML is being executed.

{{{
Starting ACPI debugger.
Evaluate _Q66():
  Op: 0x002d INT_NAMEPATH_OP      [0x02 ARGUMENT]
  Op: 0x000a BYTE_OP              [0x02 ARGUMENT]
  Op: 0x0093 LEQUAL_OP            [0x00 EXECUTE]
  Op: 0x0092 LNOT_OP              [0x00 EXECUTE]
  Op: 0x00a0 IF_OP                [0x04 CONTROL]
  Op: 0x0035 INT_METHODCALL_OP    [0x09 METHOD_CALL]
Call NEVT():
  Op: 0x0035 INT_METHODCALL_OP    [0x09 METHOD_CALL]
Call ECG1():
  Op: 0x000a BYTE_OP              [0x02 ARGUMENT]
  Op: 0x0035 INT_METHODCALL_OP    [0x09 METHOD_CALL]
Call ECRW():
  Op: 0x0068 ARG0                 [0x02 ARGUMENT]
  Op: 0x0035 INT_METHODCALL_OP    [0x09 METHOD_CALL]
Call ECR2():
  Op: 0x0068 ARG0                 [0x02 ARGUMENT]
  Op: 0x0035 INT_METHODCALL_OP    [0x09 METHOD_CALL]
Call ECR1():
  Op: 0x002d INT_NAMEPATH_OP      [0x02 ARGUMENT]
  Op: 0x000a BYTE_OP              [0x02 ARGUMENT]
  Op: 0x0093 LEQUAL_OP            [0x00 EXECUTE]
  Op: 0x00a0 IF_OP                [0x04 CONTROL]
}}}