I use kernel.org docs to read about kernel functions. Now I am trying to make possible reading manuals for kernel-mode functions, such as printk with man 9 printk. The section 9 is used for this purpose: from man man section descriptions:
9 - Kernel routines [Non standard]
Running make mandocs at /usr/src/linux/ throws this:
make: *** No rule to make target 'mandocs'. Stop.
(I think mandocs is obsolete or was removed). I cannot find man9 packages on my Gentoo GNU/Linux system. Also, I tried to install those manpages on Debian 11 virtual machine, but it fails too.
How can I install/make/download those non-standard manpages for kernel functions to be able to run man printk to get docs without having to search documentation online or browsing header files?
I know that similar questions were already asked (this and this), but they are deprecated (no make mandocs now).