On Wed, Feb 20, 2019 at 6:00 PM Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> wrote: > On 2/20/19 5:51 PM, Arnd Bergmann wrote: > > On Wed, Feb 20, 2019 at 3:45 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> 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