I got the impression a while back that using "/usr/src/linux" causes problem and you shouldn't use it as a link. I am only seeing everyone using links to "/usr/src/linux". Has someone changed their mind?

There's nothing actually wrong with having /usr/src/linux be a link to the source tree it just isn't the canonical location anymore (that's /lib/modules/`uname -r`/build). I generally build kernels in /usr/src/linux-`uname -r` with /usr/src/linux being a symlink to the current kernel. It's quicker to type and I know what it means however scripts shouldn't use it as there's no guarantee that it exists or is correct (the /lib/modules path is created by kernel makefiles (make modules_install I think) and so is (almost) guaranteed to be correct).

I generally go by what the README in my source files says. Like for making the kernel:

Why not just extract the kernel sources in /home/name/build/kernel in this case ?

I have done that in the past but prefer the proper place with root ownership. If I want to start again I know I have the untouched kernel source still in /usr/src. It's the german in me!

I have two levels of indirection:

/usr/src/linux -> /home/blah/blah/kernel/linux/src
and
/home/blah/blah/kernel/linux -> ./linux/2.6.10

non-root ownership of course! Then just 'sudo make install' (safer)

never had problems.
nvidia compiles OK anyway.

Can then switch patch levels and everything easily.
Just need to change the last from say 2.6.9 to 2.6.10 nothing else to do.

I can also switch compiling between distros as my home is a partition of course
and I don't lose the state if I do an install.

you can always do a make clean to get back to original (or make a tar.bz2 b4 you compile)

the prohabition against using /usr/src/linux is something old
once a glibc developer practice of having some of the user space includes as symlinks to i think /usr/src/linux/asm or something got mistakenly bled into some distributions..
this caused the kernel developers to freak out and declare /usr/src/linux as a wrong thing

since /usr/src/linux is something left over from the very begining of building linux systems people sometimes associate these old wrongs with /usr/src/linux itself

there are still to this day especially solaris style builds and third paty junk like nvidia drivers that look for currently running linux kernel headers in /usr/src/linux so it can be a big help to have it there

just make sure if you use it you keep it current with what kernel you are running

on modern systems /usr/src/linux is not a problem

often people say scripts from outside Linux circles shouldn't use it but they do and it causes no harm so i don't see the problem.

a box without /usr/src/linux well just feels like some preconfigured appliance used to deliver adds to it's user ala M$