linux/scripts/Kconfig.include

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# SPDX-License-Identifier: GPL-2.0-only
# Kconfig helper macros
# Convenient variables
comma := ,
quote := "
squote := '
empty :=
space := $(empty) $(empty)
dollar := $
right_paren := )
left_paren := (
# $(if-success,<command>,<then>,<else>)
# Return <then> if <command> exits with 0, <else> otherwise.
if-success = $(shell,{ $(1); } >/dev/null 2>&1 && echo "$(2)" || echo "$(3)")
# $(success,<command>)
# Return y if <command> exits with 0, n otherwise
success = $(if-success,$(1),y,n)
# $(failure,<command>)
# Return n if <command> exits with 0, y otherwise
failure = $(if-success,$(1),n,y)
# $(cc-option,<flag>)
# Return y if the compiler supports <flag>, n otherwise
2020-06-14 14:43:41 +00:00
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-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 -)
# check if $(CC) and $(LD) exist
$(error-if,$(failure,command -v $(CC)),compiler '$(CC)' not found)
$(error-if,$(failure,command -v $(LD)),linker '$(LD)' not found)
kbuild: check the minimum compiler version in Kconfig Paul Gortmaker reported a regression in the GCC version check. [1] If you use GCC 4.8, the build breaks before showing the error message "error Sorry, your version of GCC is too old - please use 4.9 or newer." I do not want to apply his fix-up since it implies we would not be able to remove any cc-option test. Anyway, I admit checking the GCC version in <linux/compiler-gcc.h> is too late. Almost at the same time, Linus also suggested to move the compiler version error to Kconfig time. [2] I unified the two similar scripts, gcc-version.sh and clang-version.sh into cc-version.sh. The old scripts invoked the compiler multiple times (3 times for gcc-version.sh, 4 times for clang-version.sh). I refactored the code so the new one invokes the compiler just once, and also tried my best to use shell-builtin commands where possible. The new script runs faster. $ time ./scripts/clang-version.sh clang 120000 real 0m0.029s user 0m0.012s sys 0m0.021s $ time ./scripts/cc-version.sh clang Clang 120000 real 0m0.009s user 0m0.006s sys 0m0.004s cc-version.sh also shows an error message if the compiler is too old: $ make defconfig CC=clang-9 *** Default configuration is based on 'x86_64_defconfig' *** *** Compiler is too old. *** Your Clang version: 9.0.1 *** Minimum Clang version: 10.0.1 *** scripts/Kconfig.include:46: Sorry, this compiler is not supported. make[1]: *** [scripts/kconfig/Makefile:81: defconfig] Error 1 make: *** [Makefile:602: defconfig] Error 2 The new script takes care of ICC because we have <linux/compiler-intel.h> although I am not sure if building the kernel with ICC is well-supported. [1]: https://lore.kernel.org/r/20210110190807.134996-1-paul.gortmaker@windriver.com [2]: https://lore.kernel.org/r/CAHk-=wh-+TMHPTFo1qs-MYyK7tZh-OQovA=pP3=e06aCVp6_kA@mail.gmail.com Fixes: 87de84c9140e ("kbuild: remove cc-option test of -Werror=date-time") Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Tested-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Tested-by: Miguel Ojeda <ojeda@kernel.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-01-15 23:35:42 +00:00
# Get the compiler name, version, and error out if it is not supported.
cc-info := $(shell,$(srctree)/scripts/cc-version.sh $(CC))
$(error-if,$(success,test -z "$(cc-info)"),Sorry$(comma) this compiler is not supported.)
cc-name := $(shell,set -- $(cc-info) && echo $1)
cc-version := $(shell,set -- $(cc-info) && echo $2)
kbuild: check the minimum assembler version in Kconfig Documentation/process/changes.rst defines the minimum assembler version (binutils version), but we have never checked it in the build time. Kbuild never invokes 'as' directly because all assembly files in the kernel tree are *.S, hence must be preprocessed. I do not expect raw assembly source files (*.s) would be added to the kernel tree. Therefore, we always use $(CC) as the assembler driver, and commit aa824e0c962b ("kbuild: remove AS variable") removed 'AS'. However, we are still interested in the version of the assembler acting behind. As usual, the --version option prints the version string. $ as --version | head -n 1 GNU assembler (GNU Binutils for Ubuntu) 2.35.1 But, we do not have $(AS). So, we can add the -Wa prefix so that $(CC) passes --version down to the backing assembler. $ gcc -Wa,--version | head -n 1 gcc: fatal error: no input files compilation terminated. OK, we need to input something to satisfy gcc. $ gcc -Wa,--version -c -x assembler /dev/null -o /dev/null | head -n 1 GNU assembler (GNU Binutils for Ubuntu) 2.35.1 The combination of Clang and GNU assembler works in the same way: $ clang -no-integrated-as -Wa,--version -c -x assembler /dev/null -o /dev/null | head -n 1 GNU assembler (GNU Binutils for Ubuntu) 2.35.1 Clang with the integrated assembler fails like this: $ clang -integrated-as -Wa,--version -c -x assembler /dev/null -o /dev/null | head -n 1 clang: error: unsupported argument '--version' to option 'Wa,' For the last case, checking the error message is fragile. If the proposal for -Wa,--version support [1] is accepted, this may not be even an error in the future. One easy way is to check if -integrated-as is present in the passed arguments. We did not pass -integrated-as to CLANG_FLAGS before, but we can make it explicit. Nathan pointed out -integrated-as is the default for all of the architectures/targets that the kernel cares about, but it goes along with "explicit is better than implicit" policy. [2] With all this in my mind, I implemented scripts/as-version.sh to check the assembler version in Kconfig time. $ scripts/as-version.sh gcc GNU 23501 $ scripts/as-version.sh clang -no-integrated-as GNU 23501 $ scripts/as-version.sh clang -integrated-as LLVM 0 [1]: https://github.com/ClangBuiltLinux/linux/issues/1320 [2]: https://lore.kernel.org/linux-kbuild/20210307044253.v3h47ucq6ng25iay@archlinux-ax161/ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
2021-03-15 16:12:56 +00:00
# Get the assembler name, version, and error out if it is not supported.
as-info := $(shell,$(srctree)/scripts/as-version.sh $(CC) $(CLANG_FLAGS))
$(error-if,$(success,test -z "$(as-info)"),Sorry$(comma) this assembler is not supported.)
as-name := $(shell,set -- $(as-info) && echo $1)
as-version := $(shell,set -- $(as-info) && echo $2)
kbuild: check the minimum linker version in Kconfig Unify the two scripts/ld-version.sh and scripts/lld-version.sh, and check the minimum linker version like scripts/cc-version.sh did. I tested this script for some corner cases reported in the past: - GNU ld version 2.25-15.fc23 as reported by commit 8083013fc320 ("ld-version: Fix it on Fedora") - GNU ld (GNU Binutils) 2.20.1.20100303 as reported by commit 0d61ed17dd30 ("ld-version: Drop the 4th and 5th version components") This script show an error message if the linker is too old: $ make LD=ld.lld-9 SYNC include/config/auto.conf *** *** Linker is too old. *** Your LLD version: 9.0.1 *** Minimum LLD version: 10.0.1 *** scripts/Kconfig.include:50: Sorry, this linker is not supported. make[2]: *** [scripts/kconfig/Makefile:71: syncconfig] Error 1 make[1]: *** [Makefile:600: syncconfig] Error 2 make: *** [Makefile:708: include/config/auto.conf] Error 2 I also moved the check for gold to this script, so gold is still rejected: $ make LD=gold SYNC include/config/auto.conf gold linker is not supported as it is not capable of linking the kernel proper. scripts/Kconfig.include:50: Sorry, this linker is not supported. make[2]: *** [scripts/kconfig/Makefile:71: syncconfig] Error 1 make[1]: *** [Makefile:600: syncconfig] Error 2 make: *** [Makefile:708: include/config/auto.conf] Error 2 Thanks to David Laight for suggesting shell script improvements. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org>
2021-02-16 03:10:04 +00:00
# Get the linker name, version, and error out if it is not supported.
ld-info := $(shell,$(srctree)/scripts/ld-version.sh $(LD))
$(error-if,$(success,test -z "$(ld-info)"),Sorry$(comma) this linker is not supported.)
ld-name := $(shell,set -- $(ld-info) && echo $1)
ld-version := $(shell,set -- $(ld-info) && echo $2)
kconfig: introduce m32-flag and m64-flag When a compiler supports multiple architectures, some compiler features can be dependent on the target architecture. This is typical for Clang, which supports multiple LLVM backends. Even for GCC, we need to take care of biarch compiler cases. It is not a problem when we evaluate cc-option in Makefiles because cc-option is tested against the flag in question + $(KBUILD_CFLAGS). The cc-option in Kconfig, on the other hand, does not accumulate tested flags. Due to this simplification, it could potentially test cc-option against a different target. At first, Kconfig always evaluated cc-option against the host architecture. Since commit e8de12fb7cde ("kbuild: Check for unknown options with cc-option usage in Kconfig and clang"), in case of cross-compiling with Clang, the target triple is correctly passed to Kconfig. The case with biarch GCC (and native build with Clang) is still not handled properly. We need to pass some flags to specify the target machine bit. Due to the design, all the macros in Kconfig are expanded in the parse stage, where we do not know the target bit size yet. For example, arch/x86/Kconfig allows a user to toggle CONFIG_64BIT. If a compiler flag -foo depends on the machine bit, it must be tested twice, one with -m32 and the other with -m64. However, -m32/-m64 are not always recognized. So, this commits adds m64-flag and m32-flag macros. They expand to -m32, -m64, respectively if supported. Or, they expand to an empty string if unsupported. The typical usage is like this: config FOO bool default $(cc-option,$(m64-flag) -foo) if 64BIT default $(cc-option,$(m32-flag) -foo) This is clumsy, but there is no elegant way to handle this in the current static macro expansion. There was discussion for static functions vs dynamic functions. The consensus was to go as far as possible with the static functions. (https://lkml.org/lkml/2018/3/2/22) Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: George Spelvin <lkml@sdf.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
2020-03-10 10:12:49 +00:00
# machine bit flags
# $(m32-flag): -m32 if the compiler supports it, or an empty string otherwise.
# $(m64-flag): -m64 if the compiler supports it, or an empty string otherwise.
cc-option-bit = $(if-success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null,$(1))
m32-flag := $(cc-option-bit,-m32)
m64-flag := $(cc-option-bit,-m64)