> I checked in the MIPS documentation and I couldn't find relevant
> information about this particular way of implementation. Unfortunately
> in the MIPS kernel source there are no enough comments.
With reasonable understanding what the MIPS architecture features covered
by these macros, functions, etc. are you should be able to infer from
Linux code what it actually does.
May I suggest some reading on the architecture first then? I realise
MIPS Technologies' architecture specifications may not be the best way to
learn how the architecture works, so why not try a MIPS textbook instead,
such as Dominic Sweetman's excellent "See MIPS Run Linux" (ISBN
978-0-12-088421-6)? While not covering such details of Linux as you are
looking for, it includes related introductory subjects to get you started.
And of course it covers the MIPS architecture itself. You may be able to
find the book at your nearby (or less near) library.
I think it's about as much as we can help -- you need to get down to
understanding the details yourself or you'll be bound to asking around
helplessly all the time.