Kernel taint state descriptions

It seems I always have to search for the kernel taint descriptions. So for reference they’re located in kernel/panic.c of the kernel source.

The descriptions are as follows:

/**
 *	print_tainted - return a string to represent the kernel taint state.
 *
 *  'P' - Proprietary module has been loaded.
 *  'F' - Module has been forcibly loaded.
 *  'S' - SMP with CPUs not designed for SMP.
 *  'R' - User forced a module unload.
 *  'M' - System experienced a machine check exception.
 *  'B' - System has hit bad_page.
 *  'U' - Userspace-defined naughtiness.
 *  'D' - Kernel has oopsed before
 *  'A' - ACPI table overridden.
 *  'W' - Taint on warning.
 *  'C' - modules from drivers/staging are loaded.
 *  'I' - Working around severe firmware bug.
 *  'O' - Out-of-tree module has been loaded.
 *
 *	The string is overwritten by the next call to print_tainted().
 */

I run into W regularly but as I don’t tend to use binary drivers, third party firmwares, force module loads or use custom ACPI tables (I wonder if a T for custom/out of tree Device Tree is needed?) I don’t tend to see many of the others. I do use staging drivers though. The other one I see quite regularly that isn’t documented in the above comment is G which means “GPL module loaded” ie basically the opposite to P “Proprietary”.