| Message ID | 1512835350-8646-1-git-send-email-yamada.masahiro@socionext.com |
|---|---|
| Headers | show |
| Series | kbuild,kconfig: generate lexer/parser C files instead of copying _shipped files | expand |
2017-12-10 1:02 GMT+09:00 Masahiro Yamada <yamada.masahiro@socionext.com>: > 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 > I did not get any problem report from the 0-day bot. I assume flex and bison are installed on their machines. Fixed a typo pointed out by Randy, then applied to linux-kbuild/kconfig. -- Best Regards Masahiro Yamada
Hi Masahiro. > > 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. ... Nice cleanup we should have does years ago. When we introduced this we did this to minimize the time it took to configure a clean kernel - as one of the reasons. Since then the average computer has been significantly faster so the time to run flex/bison is not an issue anymore. Sam