kconfig: unify cc-option and as-option (4d0831e8) · Commits · 戴 / test

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 (-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 commit ("Makefile: Improve compressed debug info support detection"), but the assembler should always be invoked for more reliable compiler option tests. However, you cannot simply replace -S with -c because the following code in lib/Kconfig.debug 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@kernel.org> Acked-by:

Will Deacon <will@kernel.org>

arch/arm64/Kconfig

+1 −1

Original line number	Diff line number	Diff line
		@@ -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)

lib/Kconfig.debug

+0 −1

Original line number	Diff line number	Diff line
		@@ -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

scripts/Kconfig.include

+1 −7

Original line number	Diff line number	Diff line
		@@ -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 -)

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