2018-02-08 9:57 GMT+09:00 Kees Cook <keescook@xxxxxxxxxxxx>: > On Thu, Feb 8, 2018 at 10:44 AM, Masahiro Yamada > <yamada.masahiro@xxxxxxxxxxxxx> wrote: >> 2018-02-08 2:55 GMT+09:00 Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>: >>> What I would really want - and this is entirely unrelated to this >>> particular case - is to have those damn compiler option tests as part >>> of the config phase in general. We now have about a million of these >>> crazy things, where we have config options that simply depend on which >>> compiler we have, and we have no sane way to show them at >>> configuration time. >>> >>> Though Andrew's tree I got yet another ugly hack >>> (CONFIG_CC_STACKPROTECTOR_AUTO) that handles just _one_ special case >>> by turning it into a special magic Kconfig entry in the main Makefile. >>> See commit 44c6dc940b19 ("Makefile: introduce >>> CONFIG_CC_STACKPROTECTOR_AUTO"). I wasn't sure if I really wanted it, >>> and honestly, I'm still thinking of just reverting it, because it's >>> _so_ ugly and _so_ wrong. >>> >>> What we need is an extension to the Kconfig language itself so that we can do >>> >>> config CC_HAS_RETPOLINE >>> cc_option "-mindirect-branch=thunk -mindirect-branch-table" >>> >>> or something. And then we can make sane _conditional_ dependencies at >>> Kconfig time, and our makefiles would be much cleaner too when you >>> could just do >>> >>> cflags-$(USE_RETPOLINE) += -mfunction-return=thunk -mindirect-branch-table >>> >>> because the validity of the C compiler flag has been tested when configuring. >>> >>> And then we could add that warning at configure time (or just disable >>> the option there thanks to "depends on CC_HAS_xyz" logic). >>> >>> All our compiler option handling right now is just nasty nasty nasty crud. >>> >>> Adding more people in the hopes that somebody gets motivated.. I've >>> talked about this before, so far we haven't made any progress. >> >> >> Sorry for slow progress. >> >> I agreed this before, and still motivated. >> (because I also motivated to remove kbuild cache. >> This turned out not so clever as I first thought) >> >> I was trying to do this, but in this development cycle >> I spent most of my time to flush out lots of piled up Kconfig patches. >> Sorry. >> >> Unless somebody is working, I will. I sent the first draft. For people interested, I pushed the series in the following too. git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kconfig-opt-shell-rfc -- Best Regards Masahiro Yamada -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html