Sangoma Kernel Tainted

This issue comes up a lot when some of our clients ( at work ) have Sangoma analog or T1 cards and start digging around the logs. This is often thought to be a problem and source of problems with dropped calls or call quality issues ( which are more often than not related to the carrier, not the Sangoma card or PBX ).

Anyway, I just wanted to have a good place to grab the answer to the question "What does kernel tainted mean and how can I fix it?". The answer of course is that it doesn't matter and can be safely ignored unless we're going to be reporting stuff to the linux kernel developers for something totally unrelated.

Here are the details from kernel.org:

What does it mean for a module to be tainted?

* (REG, contributed by John Levon) Some vendors distribute binary modules (i.e. modules without available source code under a free software license). As the source is not freely available, any bugs uncovered whilst such modules are loaded cannot be investigated by the kernel hackers. All problems discovered whilst such a module is loaded must be reported to the vendor of that module, not the Linux kernel hackers and the linux-kernel mailing list. The tainting scheme is used to identify bug reports from kernels with binary modules loaded: such kernels are marked as "tainted" by means of the MODULE_LICENSE tag. If a module is loaded that does not specify an approved license, the kernel is marked as tainted. The canonical list of approved license strings is in linux/include/linux/module.h.
"oops" reports marked as tainted are of no use to the kernel developers and will be ignored. A warning is output when such a module is loaded. Note that you may come across module source that is under a compatible license, but does not have a suitable MODULE_LICENSE tag. If you see a warning from modprobe or insmod for a module under a compatible license, please report this bug to the maintainers of the module, so that they can add the necessary tag.
* (KO) If a symbol has been exported with EXPORT_SYMBOL_GPL then it appears as unresolved for modules that do not have a GPL compatible MODULE_LICENSE string, and prints a warning. A module can also taint the kernel if you do a forced load. This bypasses the kernel/module verification checks and the result is undefined, when it breaks you get to keep the pieces.
* (KO) According to Alan Cox, a license of "BSD without advertisement clause" is not a suitable free software license. This license type allows binary only modules without source code. Any modules in the kernel tarball with this license should really be "Dual BSD/GPL".

-- JeffreyWeitz - 2010-11-01

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