--- title: ACPI AML Runtime Debugger in Ubuntu 18.04 (x64) description: The aml-debugger.txt is the instruction for enabling AML run-time debugger. This document is available at Documentation/acpi/ in Linux kernel source code. url: https://canonical.com/blog/acpi-aml-runtime-debugger-in-ubuntu-18-04-x64?format=md --- 1. [Blog](https://canonical.com/blog) 2. Article --- [Alex Hung](https://canonical.com/blog/author/alexhung "More about Alex Hung") 14 February 2019 # ACPI AML Runtime Debugger in Ubuntu 18.04 (x64) [ACPI](https://canonical.com/blog/tag/acpi) [Debugging](https://canonical.com/blog/tag/debugging) [Ubuntu Desktop](https://canonical.com/blog/tag/ubuntu-desktop) --- Share the article [ACPICA](https://www.acpica.org/) is an open-source project that provides an operating system (OS)-independent reference implementation. It also contains a list of utilities such as ASL compiler (iasl), acpiexec (an AML emulator). However, AML debugging on Linux in run-time wasn’t provided in ACPICA until Linux Kernel 4.13. ## Enabling AML Debugging The [aml-debugger.txt](https://github.com/torvalds/linux/blob/master/Documentation/acpi/aml-debugger.txt) is the instruction for enabling AML run-time debugger. This document is available at Documentation/acpi/ in Linux kernel source code. In short, two things are required for AML run-time debugging * Enable AML debugging (**CONFIG\_ACPI\_DEBUGGER**=y & **CONFIG\_ACPI\_DEBUGGER\_USER**=m) when compiling Linux kernel * Compile an utility, **acpidbg** from Linux kernel (I uploaded a copy [here](http://people.canonical.com/~alexhung/acpidbg)) While compiling a custom-build kernel is nothing new to kernel developers, it is often inconvenient for system firmware / BIOS developers. Fortunately, Ubuntu 18.04 (x64) and later enable these config by default. One can simply execute ***acpidbg*** on Ubuntu 18.04 – even on Ubuntu Live from USB too! Note: acpidbg can be installed by the following command on Ubuntu ``` sudo apt install linux-tools-`uname -r` linux-tools-generic ``` ## Running AML Debugging Executing acpidbg on Ubuntu 18.04 (x64) is straight-forward ``` $ sudo ./acpidbg - ``` and “help” shows a list supported commands ``` - help General-Purpose Commands: ... ... Namespace Access Commands: ... ... Control Method Execution Commands: ... ... ``` ## Examples ***acpidbg*** is particularly handy when one needs to evaluate any ACPI AML objects during run-time – especially ones that change under different conditions. This may be explained by some examples below: **Example 1** – To determine AC power status in run-time. 1. Find \_PSR objects 2. Evaluate \_PSR when AC is disconnected 3. Evaluate \_PSR when AC is connected ``` - find _PSR \_SB.PCI0.LPC.EC.AC._PSR Method 00000000c53d0a47 01 Args 0 Len 0023 Aml 00000000eab88cb2 - execute \_SB.PCI0.LPC.EC.AC._PSR Evaluating \_SB.PCI0.LPC.EC.AC._PSR Evaluation of \_SB.PCI0.LPC.EC.AC._PSR returned object 00000000c46fa555, external buffer length 18 [Integer] = 0000000000000000 - execute \_SB.PCI0.LPC.EC.AC._PSR Evaluating \_SB.PCI0.LPC.EC.AC._PSR Evaluation of \_SB.PCI0.LPC.EC.AC._PSR returned object 00000000c46fa555, external buffer length 18 [Integer] = 0000000000000001 ``` ***acpidbg*** also works with complex objects such as packages. **Example 2** – To determine battery information and status 1. Find \_BIF and \_BST objects 2. Evaluate \_BIF and \_BST objects (note \_BST changes dynamically). ``` - find _BIF \_SB.PCI0.LPC.EC.BAT0._BIF Method 00000000817541c3 01 Args 0 Len 0040 Aml 000000009abb252e - execute \_SB.PCI0.LPC.EC.BAT0._BIF Evaluating \_SB.PCI0.LPC.EC.BAT0._BIF Evaluation of \_SB.PCI0.LPC.EC.BAT0._BIF returned object 00000000c46fa555, external buffer length 170 [Package] Contains 13 Elements: [Integer] = 0000000000000000 [Integer] = 000000000000ABE0 [Integer] = 0000000000009E34 [Integer] = 0000000000000001 [Integer] = 0000000000003B60 [Integer] = 00000000000007E9 [Integer] = 00000000000000C8 [Integer] = 0000000000000001 [Integer] = 0000000000000001 [String] Length 07 = "00HW027" [String] Length 05 = " 409" [String] Length 03 = "LiP" [String] Length 03 = "SMP" - find _BST \_SB.PCI0.LPC.EC.BAT0._BST Method 00000000ed98c5ba 01 Args 0 Len 001D Aml 00000000a48eaeb6 - execute \_SB.PCI0.LPC.EC.BAT0._BST Evaluating \_SB.PCI0.LPC.EC.BAT0._BST Evaluation of \_SB.PCI0.LPC.EC.BAT0._BST returned object 00000000c46fa555, external buffer length 78 [Package] Contains 4 Elements: [Integer] = 0000000000000001 [Integer] = 00000000000010C6 [Integer] = 00000000000088B8 [Integer] = 0000000000003FC9 ``` **acpidbg** can decode bit fields and save time on counting bits. Try to run acpidbg to evaluate any \_PLD objects and you will see what I mean :). ## Sign up for our newsletter Get the latest Canonical news and updates in your inbox. Work email: \*I agree to receive information about Canonical's products and services. By submitting this form, I confirm that I have read and agree to [Canonical's Privacy Policy](https://canonical.com/legal/dataprivacy). Sign up ## Share on --- ## Related posts [### Arduino® VENTUNO™ Q is available for pre-order with Ubuntu pre-installed](https://canonical.com/blog/arduino-ventuno-q-is-available-for-pre-order-with-ubuntu-pre-installed) London, UK – August 25, 2026 – Following our initial collaboration announcement in March 2026, Canonical and Arduino (a subsidiary of Qualcomm Technologies, Inc.) are excited... 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