I am using an Android Custom ROM on my device, also with a custom boot.img (custom kernel + cmdline + ramdisk). I now want to be able to view the kernel logs immediately after a kernel panic, but unfortunately I can not use a serial console.
The good news: There seem to be some sources/modules in the Linux kernel of Android that are written exactly for this purpose. For example, the following lines are activated in my .config file for the kernel:
CONFIG_ANDROID_RAM_CONSOLE=y
CONFIG_ANDROID_RAM_CONSOLE_ENABLE_VERBOSE=y
CONFIG_APANIC=y
CONFIG_APANIC_PLABEL="oem_log"
My problem is: After I forced a kernel panic in order to test this, i.e. by loading a simple panic kernel module with insmod panic.ko, it seems that no log was written to the MTD named oem_log (which exists on my device). Secondly, the RAM also does not contain logs after reboot because it seems to be cleared - or the logs are not written either.
So how can I get the kernel logs after a panic? Also it would be helpful if there is a way I could test the APANIC on the running system. Maybe by using the kernel debug system? As of now I am pretty new to this.
Thanks in advance for any help!
As for me,
cat /proc/last_kmsg
after reboot (caused by the kernel panic during insmod) does list messages relevant to the crash, like
[ 424.909515] Kernel panic - not syncing: Fatal exception
[ 424.909606] Backtrace:
[ 424.909790] [<c005a5ec>] (dump_backtrace+0x0/0x10c) from [<c05f38dc>] (dump_stack+0x18/0x1c)
[ 424.909973] r6:c5cccf00 r5:00000000 r4:c08505a0 r3:00000000
So you can at least try. I am working with Linux 3.0.31-g4f6d371 on Galaxy Nexus.