Kninja is an experimental Ninja build file
generator for Kbuild, the Linux kernel's build system. It does not really
attempt to understand Kbuild files but instead just processes the output
generated by GNU Make's --print-data-base. Configuration changes and changes
to files with special generation rules are not currently handled, but
modifications to most normal source and header files should just work.
The use of ninja results in vastly improved incremental build times:
| Change | make -j8 | make -j8 objectname | ninja |
|---|---|---|---|
| No changes | 2.254s | 0.731s | 0.065s |
| One change, compile error | 1.225s | 0.765s | 0.077s |
| One change, full link | 5.915s | NA | 4.482s |
The link time unsuprisingly dominates when performing small changes, but as can be seen the time until the start of compilation (and thus the time until any compile errors are detected) is several times smaller with ninja.
These numbers were measured with the benchmarking script included in the repository. Reading that script should also give you an example of how to use kninja.
Python 3.4+ is required. Install the required packages with:
pip3 install -r requirements.txt
Run kninja.py to generate Ninja build files. This must also be run manually
after any changes to .config or Makefiles.
$ kninja.py
[INFO] Ensuring full build: make -j 8
CHK include/config/kernel.release
CHK include/generated/uapi/linux/version.h
CHK include/generated/utsrelease.h
CHK include/generated/timeconst.h
CHK include/generated/bounds.h
CHK include/generated/asm-offsets.h
CALL scripts/checksyscalls.sh
CHK include/generated/compile.h
Building modules, stage 2.
MODPOST 18 modules
Kernel: arch/x86/boot/bzImage is ready (#6)
[INFO] Generating make database: make -p
[INFO] Caching make database to .makedb
[INFO] Parsing make database (2635077 lines)
[INFO] Wrote build.ninja (2763 rules, 2744 build statements)
[INFO] Wrote .ninja_deps (2155 targets, 939990 deps)
[INFO] Wrote .ninja_log (2763 commands)
[INFO] Checking ninja status: ninja -d explain -n
[INFO] All OK