Linux Kernel configs official documentation

Question

When compiling a linux kernel, one of the first step is to generate the .config file which in my case I'm getting from the currently installed kernel. So it generates this files with a lot of KEY=VALUES like:

CONFIG_64BIT=y
CONFIG_X86_64=y
CONFIG_X86=y
CONFIG_INSTRUCTION_DECODER=y
CONFIG_OUTPUT_FORMAT="elf64-x86-64"
CONFIG_ARCH_DEFCONFIG="arch/x86/configs/x86_64_defconfig"
CONFIG_STACKTRACE_SUPPORT=y
# etc...

I can just copy/paste one of those keys in google and I'll probably find (in some random site) a detailed explanation for what it is used for. So my question is, is there an official place where I can rely to know about those configs? I searched on kernel.org/doc and didn't found so I decided to ask here. Thanks in advance.

Answer 1

The documentation can be access through the make menuconfig, each entry is documented (a paragraph describes the option).

But you can only see the options that are available to your architecture, and also if you disable a feature it may hide some related option.

If you want to see all options, the best thing it is to open the Kconfig files. You can go here: https://github.com/torvalds/linux/ and search for Kconfig files (There are at this moment 1021 Kconfig files)

But clearly if you do not know where to search, for example if you are looking for CONFIG_INSTRUCTION_DECODER, from the kernel source tree run: grep INSTRUCTION_DECODER $(find -name Kconfig)

But INSTRUCTION_DECODER is not really a good example since there is no associated help section with that option...