Keeping external kernel modules from being deleted (Shallow Thoughts)

Akkana's Musings on Open Source Computing and Technology, Science, and Nature.

Wed, 24 Jun 2009

Keeping external kernel modules from being deleted

I've been enjoying my random system beeps, different every day. At least up until yesterday, when I didn't seem to have one. Today I didn't have one either, and discovered that was because the beep module was no longer loaded.

Why not? Well, I updated my kernel to tweak some ACPI parameters (fruitlessly, as it turns out; I'm trying to get powertop to give me more information but I haven't found the magic combination of kernel parameters it wants on this machine) and so I did a make modules_install. And it seems that make modules_install starts out by doing rm -rf /lib/modules/VERSION/kernel which removed my externally built beep module along with everything else.

I couldn't find documentation on this, but I did find Intel Wireless bug 556 which talks about the issue. Apparently somewhere along the way 2.6 started doing this rm -rf, but you can get around it by installing outside the kernel directory.

In other words, instead of

cp beep.ko /lib/modules/
cp beep.ko /lib/modules/
Then your external module won't get wiped out at the next modules_install.

I've let the maintainer of Fancy Beeper know about this, so it won't be a problem for that module, but it's a good tip to know about in general -- I'm sure there are lots of modules that hit this problem.

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[ 10:30 Jun 24, 2009    More linux/kernel | permalink to this entry | ]

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