diff options
Diffstat (limited to 'scripts')
| -rw-r--r-- | scripts/Kconfig.toolchain | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/scripts/Kconfig.toolchain b/scripts/Kconfig.toolchain index 4b962831d62a..2acbd40a38f1 100644 --- a/scripts/Kconfig.toolchain +++ b/scripts/Kconfig.toolchain @@ -144,6 +144,25 @@ config CC_HAS_ASSUME config CC_HAS_NO_PROFILE_FN_ATTR def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) +# Beware of two problems when using cc-option in Kconfig compared to Kbuild +# +# 1. cc-option in Kbuild tests the provided flags with all previously added +# CFLAGS, whereas cc-option in Kconfig only tests the provided flags with a +# small, constant set of additional flags. If a flag (e.g., '-mfoo') +# depends on another (e.g, '-fbar') to function properly, the dependency +# must be included in the cc-option call (e.g, '-fbar -mfoo'). +# +# 2. Bit and endianness flags ('-m32', '-m64', '-mbig-endian', and +# '-mlittle-endian') are not present in Kconfig cc-option checks because +# they may be included in KBUILD_CFLAGS / KBUILD_CPPFLAGS based on the +# finalized configuration result. This can result in inconsistent results +# when probing toolchains that support either option, as the toolchain's +# configured default tested in Kconfig may not support the tested flag but +# the post-configuration result in Kbuild would. +# +# In general, prefer adding truly generic compiler flags to avoid this +# pitfall. + config CC_OPT_ZERO_INIT_PADDING_BITS def_string "$(cc-option-str,-fzero-init-padding-bits=all)" @@ -169,10 +188,6 @@ config CC_OPT_NO_ALLOW_STORE_DATA_RACES config CC_HAS_MNOP_MCOUNT def_bool $(cc-option,-mnop-mcount) -# s390-linux-gnu-gcc did not support -mfentry until gcc-9. -config CC_HAS_MFENTRY - def_bool $(cc-option,-mfentry) - config LD_OPT_FORCE_GROUP_ALLOCATION def_string "$(ld-option-str,--force-group-allocation)" |