cat /proc/sys/kernel/tainted prints the current kernel taint value (in base 10). My understanding is that this value is a bitfield, where each bit indicates the absence or presence of a particular type of taint. You can extract the bits using
python3 -c 'from pprint import pprint; pprint(list(zip(range(50), reversed(bin(int(open("/proc/sys/kernel/tainted").read()))[2:]))))'
I've searched for documentation, but what I've seen only identifies the meaning of bits 0 through 10. For example, http://www.kernel.org/doc/Documentation/sysctl/kernel.txt says:
tainted: Non-zero if the kernel has been tainted. Numeric values, which can be ORed together: 1 - A module with a non-GPL license has been loaded, this includes modules with no license. Set by modutils >= 2.4.9 and module-init-tools. 2 - A module was force loaded by insmod -f. Set by modutils >= 2.4.9 and module-init-tools. 4 - Unsafe SMP processors: SMP with CPUs not designed for SMP. 8 - A module was forcibly unloaded from the system by rmmod -f. 16 - A hardware machine check error occurred on the system. 32 - A bad page was discovered on the system. 64 - The user has asked that the system be marked "tainted". This could be because they are running software that directly modifies the hardware, or for other reasons. 128 - The system has died. 256 - The ACPI DSDT has been overridden with one supplied by the user instead of using the one provided by the hardware. 512 - A kernel warning has occurred. 1024 - A module from drivers/staging was loaded.
I also tried viewing the documentation for the Ubuntu kernel by installing the
linux-doc package and opening
zless /usr/share/doc/linux-doc/sysctl/kernel.txt.gz, but that still only lists up to 1024.
In my case, I'm running the default PAE kernel (3.2.0-36-generic-pae) on Precise. I am also seeing bit 12 set.
Where is the complete documentation for what the tainted bits mean on Ubuntu kernels?