cc-option and as-option are almost the same; both pass the flag to $(CC). The main difference is the cc-option stops before the assemble stage (-S option) whereas as-option stops after it (-c option). I chose -S because it is slightly faster, but $(cc-option,-gz=zlib) returns a wrong result (https://lkml.org/lkml/2020/6/9/1529). It has been fixed by a separate patch, but using -c is more robust. However, you cannot simply replace -S with -c because the following code would break: depends on $(cc-option,-gsplit-dwarf) The combination of -c and -gsplit-dwarf does not accept /dev/null as output. $ cat /dev/null | gcc -gsplit-dwarf -S -x c - -o /dev/null $ echo $? 0 $ cat /dev/null | gcc -gsplit-dwarf -c -x c - -o /dev/null objcopy: Warning: '/dev/null' is not an ordinary file $ echo $? 1 $ cat /dev/null | gcc -gsplit-dwarf -c -x c - -o tmp.o $ echo $? 0 There is another flag that creates an separate file based on the object file path: $ cat /dev/null | gcc -ftest-coverage -c -x c - -o /dev/null <stdin>:1: error: cannot open /dev/null.gcno So, we cannot use /dev/null to sink the output. Align the cc-option implementation with scripts/Kbuild.include. With -c option used in cc-option, as-option is unneeded. Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> --- arch/arm64/Kconfig | 2 +- lib/Kconfig.debug | 1 - scripts/Kconfig.include | 8 +------- 3 files changed, 2 insertions(+), 9 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 31380da53689..6eb18f45258e 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1564,7 +1564,7 @@ config CC_HAS_SIGN_RETURN_ADDRESS def_bool $(cc-option,-msign-return-address=all) config AS_HAS_PAC - def_bool $(as-option,-Wa$(comma)-march=armv8.3-a) + def_bool $(cc-option,-Wa$(comma)-march=armv8.3-a) config AS_HAS_CFI_NEGATE_RA_STATE def_bool $(as-instr,.cfi_startproc\n.cfi_negate_ra_state\n.cfi_endproc\n) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 96999d4d2dda..9ad9210d70a1 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -229,7 +229,6 @@ config DEBUG_INFO_COMPRESSED bool "Compressed debugging information" depends on DEBUG_INFO depends on $(cc-option,-gz=zlib) - depends on $(as-option,-gz=zlib) depends on $(ld-option,--compress-debug-sections=zlib) help Compress the debug information using zlib. Requires GCC 5.0+ or Clang diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include index c264da2b9b30..a5fe72c504ff 100644 --- a/scripts/Kconfig.include +++ b/scripts/Kconfig.include @@ -25,18 +25,12 @@ failure = $(if-success,$(1),n,y) # $(cc-option,<flag>) # Return y if the compiler supports <flag>, n otherwise -cc-option = $(success,$(CC) -Werror $(CLANG_FLAGS) $(1) -S -x c /dev/null -o /dev/null) +cc-option = $(success,mkdir .tmp_$$$$; trap "rm -rf .tmp_$$$$" EXIT; $(CC) -Werror $(CLANG_FLAGS) $(1) -c -x c /dev/null -o .tmp_$$$$/tmp.o) # $(ld-option,<flag>) # Return y if the linker supports <flag>, n otherwise ld-option = $(success,$(LD) -v $(1)) -# $(as-option,<flag>) -# /dev/zero is used as output instead of /dev/null as some assembler cribs when -# both input and output are same. Also both of them have same write behaviour so -# can be easily substituted. -as-option = $(success, $(CC) $(CLANG_FLAGS) $(1) -c -x assembler /dev/null -o /dev/zero) - # $(as-instr,<instr>) # Return y if the assembler supports <instr>, n otherwise as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) -c -x assembler -o /dev/null -) -- 2.25.1
