Android中抓取kernel log的步骤如下：(two methods)
1 method:

• USB connect to device.
• Start up ddms. (sdk/tools)
• Run commands

          adb root
          adb shell
          setprop persist.sys.kernel.log logcat

• Perfrom some operations. (such as a MO call)
• Check ddms log window, some kernel info will be displayed.

2 method:

$ADB -s $PARTNER_DEVICES shell cat /proc/kmsg > $RESULT_PATH/PARTNER_DEVICES_Klog.log

adb shell dmesg > ldmesg_kernel.log