In my project I configure the kernel (2.6.32) in block/ioctl.c. We all know that kernel compiling and building takes few hours. Even for a small change, I'm compiling from scratch. So is there any way to compile and build only the changed file?

  • 1
    the first question in KernelCustomBuild might help you
    – Yogu
    Apr 21, 2014 at 10:56
  • A few hours for a single .c file change? What commands are you using exactly and what hardware do you have?
    – Mat
    Apr 21, 2014 at 11:10
  • @Mat I have to analyze the block/ioctl.c code. simple ex: addind printk function. And changing some macro kind of things
    – gangadhars
    Apr 21, 2014 at 11:13
  • I understand that. Rebuilding after a small change in a .c file should not result in a complete rebuild, and even if it did that shouldn't take hours.
    – Mat
    Apr 21, 2014 at 11:14
  • 2
    Don't reconfigure if you're not changing the configuration. Don't clean if you intend to rebuild with a small change.
    – Mat
    Apr 21, 2014 at 11:26

1 Answer 1


No, kernel compiling does not take “few hours”. Linus Torvalds said that it took him 12 minutes in the old days, and a lot less these days. Of course it depends whether you're compiling a kernel with just the drivers you need for your hardware, or a distribution kernel with all the drivers people may need — but even for a distribution kernel on a slightly elderly machine, it takes way less than an hour to do a full build.

Furthermore, if you change one file of the kernel, you don't need to do a full build. Just run make (and make modules if there are modules you need to recompile), and only the changed file (and the files that depend on it, if it's a header file) will be recompiled.

  • 1
    Even the smallest change in configuration results in entire kernel being rebuilt, and it does take hours. It always did as long as I remember (20 years and counting). It became worse when deps target was dropped.
    – ajeh
    May 12, 2018 at 13:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.