Android DDMS v22.0.1 unable to generate a systrace using Droid Razor 4.1.2

Question

I've selected several of the trace tags and when I run the trace (from DDMS) I get the following output:

Unexpected error while collecting system trace. Unable to find trace start marker 'TRACE:':
error opening /sys/kernel/debug/tracing/options/overwrite: 
No such file or directory (2)

error openi(cuts off the error here)

indeed there is no debug file in the kernel directory, but which mechanism will generate the necessary path?

Answer 1

It looks like your cellphone is running a boot(kernel) image that does not support systrace.

"error opening /sys/kernel/debug/tracing/options/overwrite: No such file or directory (2)"

This error message means adb daemon (the adb module running on device side) could not find /sys/kernel/debug/tracing/options/overwrite on your device's file system. systrace works over adb and communicates with kernel though sysfs nodes under /sys/kernel/debug/tracing. If these nodes are not exposed on you phone for whatever reason, systrace just will not work.

So you should first get a shell on your device using:

adb shell

Then browse to confirm if /sys exists at all and if /sys/kernel/debug/tracing exists.

If they are there which is extremely unlikely, you have to debug systrace.py to figure out how come systrace think the nodes were not there. Otherwise, you need to flash a different boot image which has systrace support, because sysfs is controlled by kernel(mostly by configurations at compile time) and init.rc , both of which are part of boot image.

Flashing a different boot image might involve unlocking/rooting the device. You probably have to go to fan sites like xdadeveloper for information and image. Another option is to download the source of kernel for your device, compile kernel and make the boot image yourself. Linux is under GPL thus manufacturer of your device is obligated to release the source code of the specialized kernel they use.

-NAM http://www.willpromo.com