• BuildSystemImprovements

Build System Improvements

Chris & Jeremy's ideas for improvements to the k42 build system. There is also a summary of the CurrentBuildSystem.

Requirements

• correct & complete dependencies

  • builds often (silently!) fail due to stale deps
  • too much rebuilt after a small change

  • get rid of SEQ=x stuff, use make-standard -j instead

  • remove different targets (full_snapshot and fast_snapshot) - make should build exactly what is required for a complete compile.

  • use gcc -MD ?

    • you might run into problems here with dependencies on generated files (eg. headers generated by the stub compiler), which aren't there when dependency generation runs. In another project I (AB) ended up writing our own dependency generator which parsed gcc -E output, and knew enough about the specific IDL compiler (eg. MetaX.H is generated in directory A by running the stub compiler over X.H somewhere else). That's pretty ugly, but the only correct alternative is to rerun stub generation on each build before generating the main dependencies.
• reduce make output
  • just use linux's quiet cmd stuff (see the main Makefile)?
• single config file for paths, programs, etc

  • get rid of defines/ directores

  • allow a single config file for compiling which can be passed around

• 'make check' target for testing the build environment, especially external dependencies

  • eg. a missing linux source dir will cause the build to fail half-way through with no explicit error
• configurable (single!) build (output) dir, can be the same as or separate from source dir

  • eg. kernel output: make O=build-dir/

  • allows internal use of autoconf-style $objdir and $srcdir

  • source dir can be read-only

• separate build tools target (make tools ?)

  • do we need to do so much with installed scripts?
  • do we need to check tool deps on every build?
• variables for targets which handle deps automatically to facilitate development

  • eg. obj-stub += FRKernelPinned

  • per-directory makefile fragments should be as simple as possible
• efficiency
  • current system: recursive make with large amounts of rules, which need to be parsed by each invocation

• A good single-level make with properly-specified dependencies is the way to go... AB suggests skim reading recursive make considered harmful.