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" <[email protected] <javascript:>> 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.
>>
>>
>>
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