O que significa o valor do taint do kernel?

Question

A execução de cat /proc/sys/kernel/tainted imprime o valor de alteração atual do kernel (na base 10). Meu entendimento é que esse valor é um campo de bits, onde cada bit indica a ausência ou a presença de um determinado tipo de contaminação. Você pode extrair os bits usando

python3 -c 'from pprint import pprint; pprint(list(zip(range(50), reversed(bin(int(open("/proc/sys/kernel/tainted").read()))[2:]))))'

Eu procurei por documentação, mas o que eu vi só identifica o significado dos bits 0 a 10. Por exemplo, link diz:

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.
 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.

Eu também tentei visualizar a documentação para o kernel do Ubuntu instalando o pacote linux-doc e abrindo zless /usr/share/doc/linux-doc/sysctl/kernel.txt.gz , mas isso ainda lista apenas até 1024.

No meu caso, estou executando o kernel PAE padrão (3.2.0-36-generic-pae) no Precise. Eu também estou vendo o bit 12 set.

Onde está a documentação completa do que os bits contaminados significam nos kernels do Ubuntu?

    

Answer 1

Olhando para panic.c :

/**
 *      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.
 *  'E' - Unsigned module has been loaded.
 *  'L' - A soft lockup has previously occurred.
 *  'K' - Kernel has been live patched.
 *
 *      The string is overwritten by the next call to print_tainted().
 */