Android Debugging

Debugging methods for Android

Kernel and User co-debug with GDB on Android
This presentation covers lots of Android debug resources provided by Linaro, presented by Zach Pfeffer in Spring 2012. Included is information about how to debug kernel and user simultaneously with gdb.

See [[Media:Zach Pfeffer Next Gen Android 2012.pdf]]

kernel message log
The Linux kernel has a message log in an internal ring buffer. You can access the contents of this log using the 'dmesg' command.

You can add timing information to the printk messages, by adding "time" to the Linux kernel command line.

init logging
The Android init program outputs some messages to the kernel log, as it starts the system. You can increase the verbosity of init, using the "loglevel" command in the /init.rc file.

The default loglevel is 3, but you can change it to 8 (the highest) by changing the following line in the /init.rc file. Change: loglevel 3 to loglevel 8

Android logging system
The Android application framework has a built-in logging system, which goes through a special driver in the kernel. It is described at:http://developer.android.com/guide/developing/tools/adb.html#logcat

Note that although the log dumper (logcat) is described on the Android developer site on the 'adb' page, there is a native logcat command included in the Android distribution (that is, available on the target file system, which can be run locally).

strace
You can use strace on Android. It is included in the Android open source project (at least as of Android 2.1), and appears to be automatically installed in engineering builds of the software.

To use strace during early initialization, you can put it in the /init.rc file. For example, to trace zygote initialization, change the following line in /init.rc.

service zygote /system/bin/app_process -Xzygote /system/bin --zygote --start-system-server

should be changed to:

service zygote /system/xbin/strace -tt -o/data/boot.strace /system/bin/app_process -Xzygote /system/bin --zygote --start system-server

Dalvik Method Tracer
See http://developer.android.com/guide/developing/tools/traceview.html

Additional Resources

 * Google I/O 2009 - Debugging Arts of the Ninja Masters (video) by Justin Mattson