Android boot-up messages for debugging?
Related to this post I created: Does the Android emulator generate some sort of log file I can access if it crashes?
I have been searching and trying to figure out if there is any way at all to get some kind of debugging information or any kind of kernel messages from an Android phone if it gets stuck at a bootloop state? That means the phone gets stuck at the "Google" splash-screen, then crashes, then goes to that, then crashes.
I know the phone has several stages of bootloading, but for me to even figure out why my system image/modified kernel is making the phone crash, I need to at least know where the phone is crashing?
Is there any kind of log the Android emulator maybe spits out that shows it going through the stages of booting: i.e. stage 1 bootloader, main stage bootloader, kernel being loaded, initialization process, Zygote, Zygote initializing Dalvik VM, execution of system server, then boot completed (when the
ACTION_BOOT_COMPLETE flag/event is raised).
I've tried modifying
init.rc to echo commands to a boot log (but it didn't work, though I don't know if the phone makes it to that stage, all I have is a useless splash screen), I've tried any of the ADB stuff but of course ADB doesn't work if the phone doesn't reach a stable state, the Linux
dmesg command only works to show that the phone plugged in via USB, and the Android developers have chosen not to at least explain to me that only they hold those kinds of developer tools. Can anyone give me some guidance of what I can do to debug the boot process? There has to be some kind of log you can access with the emulator at least.
In other words, how does anyone get any kind of log from their phone/emulator if gets stuck in a bootloop?
Further information, my kernel version I believe I have downloaded for my phone build is Linux kernel release 3.x (stock kernel pulled from the
tuna folder and using the "omap" project), for Android Galaxy Nexus (maguro), with the platform being Android 4.0.3 ICS.