re compile kernel

[corcovado]

OK, I'm installing a stage3 gentoo 2.6 on a laptop, and I'm recompiling the kernel, because the first attempt didn't boot properly.

I changed two settings on the .config file, and the compilation was almost instantaneous. Why's that?

[hds]

because not everything gets compiled again. if you just added a module perhaps, only this one is compiled.

[corcovado]

I see, thanks.
I find that interesting.
I honestly thought even the smallest of changes would require the whole thing to be compiled again.
in the case of a small module change, *it* may be recompiled quickly, but how is it inserted into the compressed binary bzImage?

Unless of course, all kernel entities get precompiled separately and exist as binaries in the source tree. This would mean that a second phase compilation procedure take place, which compiles all these small binaries into a big one.

I suppose i really should google all this.

[hds]

well, it depends.. if you compile as module <m>, it is externally as you guessed. actually it is written running "make modules" and copied over toi /lib/modules at "make modules_install".

if you compile the module Built_in <*> it goes into bzImage.

additionally, the kernel is plenty files (name.o) wich are put together. so even if you compile your module build_in, that does not mean the complete kernel has to be rebuild. just the single part (name.o) and afterwards the binary (bzImage) is put together again, wich doesnt take long.

[cokey]

[coren2000]

make is a utility that allows programmers to not have to compile all their code when a small change has been made. since make doesn't know your not a programmer it gives you this special discount compile-time rate too:)

when you type make, make is looking to see just what source files (and I guess config files) have changed and builds the ones that have been changed, linking them to the ones that were compiled before and havn't had source changes.

[Deathwing00]

Moved from Installing Gentoo.