On Wed, Feb 20, 2019 at 6:00 PM Andrey Ryabinin <[email protected]> wrote:
> On 2/20/19 5:51 PM, Arnd Bergmann wrote:
> > On Wed, Feb 20, 2019 at 3:45 PM Andrey Konovalov <[email protected]>
> > wrote:
> > I would have to some more research, but I expect several hundred
> > patches before we get to a clean randconfig build with a broken
> > compiler.
>
> Manually maintaining asan-stack parameter for the sake of one broken compiler
> isn't a great idea either.
>
> Couple alternative suggestions:
>
> 1) If we can't fix the problem or the cost of fixing is too high, maybe just
> hide it? Disable -Wframe-larger-then on pre clang-9 compilers.
>
> 2) Fallback cflags. The idea is to try to compile every the file with "-mllvm
> -asan-stack=1 -Wframe-larger-than=2048 -Werror" at first,
> and fallback to "-mllvm -asan-stack=0" if failed. So it would be something
> similar to $(call cc-option, -mllvm -asan-stack=1 -Wframe-larger-than=2048
> -Werror, -mllvm -asan-stack=0)
> except that "cc-option" tries options only once on some code example while
> we need to try options on every file that we actually compile.
> Honestly, I'm not sure that it's worthy to hack Kbuild engine for that
> particular use-case.
My original plan was to put this under CONFIG_KASAN_EXTRA to allow you
to still enable it in older compilers, but you just removed that option ;-)
Maybe bringing it back would be a compromise? That way it's hidden from
all the build testing bots (because of the !CONFIG_COMPILE_TEST dependency),
but anyone who really wants it can still have the option, and set
CONFIG_FRAME_WARN
to whichever value they like.
Arnd
