Last time when I hacked the Linux kernel on Ubuntu, it was 4.4 on LTS 14.04. Time flies. Now I need to hack the kernel 4.13 again on LTS 16.04, and find the kernel build broken. It is fine that we could not have a stable kernel API since at least the ABI is stable. But what about kernel build?

1. “make deb-pkg” broken

This used to be my way to build a kernel on Ubuntu. If something wrong happens and stops the build, just fix the error and repeat the command again — it was incremental build. But now it is broken, as it launches “make clean” by default. Why? Because it needs to generate a source tar at first, which requires a “clean” to exclude all build artifacts[1]. Instead, use “make bindeb-pkg“.

2. VirtualBox build broken

I have no idea when Ubuntu decided to include VirtualBox guest/drivers into the kernel tree, but it is broken, because the source directory structure is different from the ones used by the makefiles. An “ln” based workaround is available[2], although I just hacked those makefiles to fix errors.

References:
[1] https://unix.stackexchange.com/questions/368864/re-building-linux-kernel-without-clean
[2] http://technote.thispage.me/index.php/2016/12/20/ubuntu-16-04-kernel-compile-on-default-setting/