In Linux build system convention, pre-generated files are version- controlled with a "_shipped" suffix. During the kernel building, they are simply shipped (copied) removing the suffix. >From users' point of view, this approach can reduce external tool dependency for the kernel build, >From developers point of view, it is tedious to manually regenerate such artifacts. In fact, we see several patches to regenerate _shipped files. They are noise commits. When we update a *.y or *.l file, it would be better to update the corresponding _shipped file in the same commit, but it is painful. If you use a different version of flex/bison, it will produce lots of irrelevant diffs. We could update _shipped files after adding various changes to the real sources, but it is not very nice for a git-bisect'ability. In case of a problem, "git bisect" would point to the commit updating _shipped files, but the root cause would be in another commit that has changed the corresponding .l or .y files. Some months ago, I sent RFC patches to run flex, bison, and gperf during the build. https://lkml.org/lkml/2017/8/19/49 Basically Linus agreed this, but he found a problem in gperf, then use of gperf in kernel was removed. It took some months for me to come back. This time, I installed various versions of flex/bison on my machine, and tested them more carefully. My current motivation is in Kconfig. There are several Kconfig patches touching *.y and *.l (and Linus suggested another improvement for Kconfig) so I want to remove zconf.lex.c_shipped and zconf.tab.c_shipped now. Kconfig has no problem for this switch. dtc and genksyms will be taken care of later because both of them are having shift/reduce conflicts now. The ambiguous grammar in dtc has been fixed in upstream, but not reflected to kernel yet. We can proceed migration in sub-system base. Masahiro Yamada (3): kbuild: add LEX and YACC variables kbuild: prepare to remove C files pre-generated by flex and bison kconfig: generate lexer and parser during build instead of shipping Documentation/process/changes.rst | 25 + Makefile | 4 +- scripts/Makefile.lib | 24 +- scripts/kconfig/Makefile | 1 + scripts/kconfig/zconf.lex.c_shipped | 2473 ----------------------------------- scripts/kconfig/zconf.tab.c_shipped | 2471 ---------------------------------- 6 files changed, 48 insertions(+), 4950 deletions(-) delete mode 100644 scripts/kconfig/zconf.lex.c_shipped delete mode 100644 scripts/kconfig/zconf.tab.c_shipped -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
