I finally managed to get a low-level debugging option using a UART terminal. And it works perfectly:
http://blog.accuvant.com/jduckandryan/building-a-nexus-4-uart-debug-cable/ (Note that Nexus 5 needs a higher input voltage, like 3.3V) 2014/1/6 Max von E <maxr...@gmail.com> > First you have to check if developer options -> USB Debuging is enabled. > Then you can (if you are root or by issuing su command in adb shell) use > dmesg to see kernel messages aswell as logcat. > If you have the sources and it's the kernel you have compiled by yourself > you can add prinkt("my messgage") to the lines you want to check, then find > it in dmesg output. > if your device is not booting and you have no chance to trace the failure > - you can check like this in the adb shell : cat /proc/last_kmesg > This will show you the last output before the device died. But in most > cases in the -user releases of kernel this option is disabled, so the best > debugging output you can get if you compile an -eng variant. > > > On Thursday, January 2, 2014 10:44:58 AM UTC+1, Marc Marí wrote: > >> When the Google screen is up, if I execute "adb devices" there are no >> devices listed. In a working Kernel, I can use adb in the inmediately next >> screen, the boot animation. >> >> I'm woking on other ideas that involve electronics and seem promising. In >> the next days I'll be able to try it. >> >> Thank you for your answer! >> On Jan 2, 2014 4:00 AM, "Eric" <sarma...@yahoo.com> wrote: >> >>> Marc Marí <5.markmb.5 <at> gmail.com> writes: >>> >>> > >>> > >>> > Hello >>> > I am new to Android and to Kernel development, but I would like to >>> test some >>> things. I just finished compiling the first version of my modified >>> kernel, and >>> put it in a phone. Obviously, it doesn't work. How can I debug the >>> kernel on >>> the mobile phone? I read things about kgdb, but I have not been able to >>> make >>> it work, any quick guides? Can I print messages to phone screen? >>> > >>> > (I am using msm kernel) >>> > >>> > Thank you in advance >>> > >>> > >>> > >>> > >>> Well, since you are using a real device, i would suggest you try >>> connecting to >>> it using ADB (android debug bridge). I've found that even when the >>> google >>> screen is still up you can connect using adb and examine the logs or poke >>> around with a text terminal. >>> >>> >>> >>> -- >>> -- >>> unsubscribe: android-kerne...@googlegroups.com >>> >>> website: http://groups.google.com/group/android-kernel >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "Android Linux Kernel Development" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to android-kerne...@googlegroups.com. >>> >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >> -- > -- > unsubscribe: android-kernel+unsubscr...@googlegroups.com > website: http://groups.google.com/group/android-kernel > --- > You received this message because you are subscribed to the Google Groups > "Android Linux Kernel Development" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to android-kernel+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. > -- -- unsubscribe: android-kernel+unsubscr...@googlegroups.com website: http://groups.google.com/group/android-kernel --- You received this message because you are subscribed to the Google Groups "Android Linux Kernel Development" group. To unsubscribe from this group and stop receiving emails from it, send an email to android-kernel+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
