file: /proc/sys/kernel/tainted
variable: kernel.tainted
Official reference

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. -2048 - The system is working around a severe firmware bug. -4096 - An out-of-tree module has been loaded. -8192 - An unsigned module has been loaded in a kernel supporting module signature. -16384 - A soft lockup has previously occurred on the system. -32768 - The kernel has been live patched.