[B.A.T.M.A.N.] reboot sometimes doesn't work well

Hi all!

Some times ago' in ninux Pisa we was experiencing kernel powering off the machine caused by batman-adv, with ordex help we debugged what was happening and the issue was solved bat that was possible because it was happening on x86 computers ( with screen )

Now it SEEMS the same is happening but on mips ( Ubiquity M devices ) but here i don't know how to make sure the problem is this, the symptoms is exactly the same, someone have idea how to save the powering off kernel output on some file so after detach/attach cable we can find what happened ?