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  1. Bug #1732651
  2. Comment #5

Comment 5 for bug 1732651

Revision history for this message
Colin Ian King (colin-king) wrote :

I tried the machine where this had failed to pass and observed that the DKMS modules for lttng had not been built by DKMS for some reason.

Looking at /var/log/apt/history.log the following happened:

1. lttng 2.8.0-1ubuntu1~16.04.2 was installed
2. new kernel 4.4.0-101 was installed
3. possibly failed to build lttng for 4.4.0-101
4. update, pulled in lttng 2.8.0-1ubuntu1~16.04.3
5. this didn't build for 4.4.0-101
6. lttng test fail because there were no lttng built modules

I just ran sudo apt-get install --reinstall lttng-modules-dkms to ensure it got rebuild and then I was able to run the tests perfectly well.

Looking at https://wiki.kubuntu.org/Kernel/Dev/DKMSPackaging it states:

"Limitation of DKMS

1. DKMS may not work well after a large change of kernel ABI - Using DKMS on a stable release kernel will be a better idea.
2. Make sure the we have toolchains and kernel header installed.
3. Using DKMS on a netbook is not a smart idea - It takes too much time to build the kernel module after kernel upgrading.
4. DKMS modules will not be loaded if there are another ones in initrd."

I wonder if the change in ABI was the issue.

I suspect the following is necessary if a large ABI change occurs:

ls /usr/src/linux-headers-* -d | sed -e 's/.*linux-headers-//' | \
> sort -V | tac | sudo xargs -n1 /usr/lib/dkms/dkms_autoinstaller start