On Sat, Aug 19, 2017 at 1:49 AM, Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> wrote: > > Here is one question. Is it acceptable to use those rules all the time? > That is, generate those C files by flex, bison, gperf during the > kernel building. Yeah, I think we probably should do that. However, when I just tested, I noticed that we have issues with re-generating those files. With gperf 3.1 installed, I get In file included from scripts/kconfig/zconf.tab.c:213:0: scripts/kconfig/zconf.gperf:147:1: error: conflicting types for ‘kconf_id_lookup’ scripts/kconfig/zconf.gperf:12:31: note: previous declaration of ‘kconf_id_lookup’ was here static const struct kconf_id *kconf_id_lookup(register const char *str, register unsigned int len); ^~~~~~~~~~~~~~~ because gperf now generates const struct kconf_id * -kconf_id_lookup (register const char *str, register unsigned int len) +kconf_id_lookup (register const char *str, register size_t len) and I'm not sure how to detect that automatically. It seems to be a gperf-3.1 change, and gperf doesn't seem to generate any version markers. Working around that, I hit: In file included from scripts/genksyms/lex.lex.c:1921:0: scripts/genksyms/keywords.gperf:54:1: error: conflicting types for ‘is_reserved_word’ static, STATIC_KEYW ^~~~~~~~~~~~~~~~ In file included from scripts/genksyms/lex.lex.c:1921:0: scripts/genksyms/keywords.gperf:6:30: note: previous declaration of ‘is_reserved_word’ was here static const struct resword *is_reserved_word(register const char *str, register unsigned int len); ^~~~~~~~~~~~~~~~ so we have at least two cases of this in the source tree. So one of the advantages of the pre-shipped files is that we can avoid that kind of crazy version issues with the tools. But if we can solve the versioning thing easily, I certainly don't mind getting rid of the pre-generated files. Having to have flex/bison/gperf isn't a huge onus on the kernel build system. Linus -- 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