如何建立freebsd内核？

Question

According to freeBSD handbook, we need to use the following targets to build the freeBSD kernel :-

make KERNCONF=config_file buildkernel

Now, even if I make a small change in a single source file, it takes a long time to compile the kernel. I am pretty sure that it is because, everything is built again including the files which were not affected in anyway.

This is creating a very big problem for me as the build time is very large (around 45 minutes) .

How can I only build the freeBSD kernel and not rebuild it ?

I have looked at the handbook and the Makefile but couldn't find any information related to it.

Answer 1

Use make KERNCONF=config_file buildkernel -DNO_CLEAN . See the build man page for more details.

PS You can put KERNCONF=config_file in /etc/make.conf and NO_CLEAN=true in /etc/src.conf to avoid having to type it every time, so you don't have a chance to accidentally forget.

Answer 2

If you only changed a piece of kernel source and not the kernel config, use KERNFAST. Like this: make buildkernel KERNFAST=1. It's so useful I've got this in my ~/.zshrc:

alias 'mbir'='make -j4 buildkernel installkernel KERNFAST=1 && reboot'