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I'm trying to get a kernel trace from the entire kernel in my virtual machine, which uses VMware Workstation 12 Player,Ubuntu 16.04.2 LTS LTS, and kernel version 4.9.40.

I have already recompiled the kernel to enable GCOV using the following instructions from the kernel source code in the /usr/src directory: sudo make menuconfig sudo make sudo make modules sudo make modules_install sudo make install

Besides that I haven't done anything drastic to the OS besides sudo apt-get update and sudo apt-get upgrade.

When I rebooted into Ubuntu with my newly recompiled, GCOV-enabled kernel, however, and I ran sudo lcov -z to reset the kernel profile, the command froze, and I was unable to stop the program from running (CTRL + Z, CTRL + C did not work) The only way I was able to end the command from running was by closing the terminal window.

The command outputs these lines on the terminal indicating that at least some part of the command is working, but always freezes after "Resetting kernel execution counters":

I did this in xterm, but you get the idea.

I have already tried uninstalling lcov, reinstalling lcov, and rebooting the virtual machine. I can't figure out what the issue is. If you have any idea why this might be happening, or how I can fix it, please let me know.

Thanks!

Mediocre Human
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  • Reseting all kernel counters can be performed *directly*, with `echo 1 > /sys/kernel/debug/gcov/reset`. Try to use this way. If it works, then something wrong with the lcov, if it doesn't work, then there is a problem with a kernel itself. – Tsyvarev Aug 01 '17 at 16:59
  • @Tsyvarev thanks for the rec - the `echo 1 > /sys/kernel/debug/gcov/reset` command didn't work so the kernel is definitely wonky. – Mediocre Human Aug 01 '17 at 19:30

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