Re: [PATCH v6] kbuild: check the minimum compiler version in Kconfig

From: Masahiro Yamada
Date: Mon Jan 18 2021 - 21:16:24 EST

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On Sat, Jan 16, 2021 at 8:36 AM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
>
> 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 the error 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@xxxxxxxxxxxxx
> [2]: https://lore.kernel.org/r/CAHk-=wh-+TMHPTFo1qs-MYyK7tZh-OQovA=pP3=e06aCVp6_kA@xxxxxxxxxxxxxx
>
> Fixes: 87de84c9140e ("kbuild: remove cc-option test of -Werror=date-time")
> Reported-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
> Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
> Tested-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
> Reviewed-by: Miguel Ojeda <ojeda@xxxxxxxxxx>
> Tested-by: Miguel Ojeda <ojeda@xxxxxxxxxx>
> Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> ---

Applied to linux-kbuild.

> Changes in v6:
> - Now that https://lore.kernel.org/r/20210112224832.10980-1-will@xxxxxxxxxx
> landed in Linus' tree, I cleaned up <linux/compiler-gcc.h> as well.
>
> Changes in v5:
> - double-quote $(cc-name) in the CC_IS_GCC and CC_IS_CLANG
>
> Changes in v4:
> - use lore version of the links
>
> Changes in v3:
> - add $(srctree)/ to fix out-of-tree build
> - support ICC version
>
> Changes in v2:
> - fix the function name
>
> include/linux/compiler-clang.h | 10 -----
> include/linux/compiler-gcc.h | 11 -----
> init/Kconfig | 9 ++--
> scripts/Kconfig.include | 6 +++
> scripts/cc-version.sh | 82 ++++++++++++++++++++++++++++++++++
> scripts/clang-version.sh | 19 --------
> scripts/gcc-version.sh | 20 ---------
> 7 files changed, 93 insertions(+), 64 deletions(-)
> create mode 100755 scripts/cc-version.sh
> delete mode 100755 scripts/clang-version.sh
> delete mode 100755 scripts/gcc-version.sh
>
> diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
> index 98cff1b4b088..04c0a5a717f7 100644
> --- a/include/linux/compiler-clang.h
> +++ b/include/linux/compiler-clang.h
> @@ -3,16 +3,6 @@
> #error "Please don't include <linux/compiler-clang.h> directly, include <linux/compiler.h> instead."
> #endif
>
> -#define CLANG_VERSION (__clang_major__ * 10000 \
> - + __clang_minor__ * 100 \
> - + __clang_patchlevel__)
> -
> -#if CLANG_VERSION < 100001
> -#ifndef __BPF_TRACING__
> -# error Sorry, your version of Clang is too old - please use 10.0.1 or newer.
> -#endif
> -#endif
> -
> /* Compiler specific definitions for Clang compiler */
>
> /* same as gcc, this was present in clang-2.6 so we can assume it works
> diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
> index 555ab0fddbef..48750243db4c 100644
> --- a/include/linux/compiler-gcc.h
> +++ b/include/linux/compiler-gcc.h
> @@ -10,17 +10,6 @@
> + __GNUC_MINOR__ * 100 \
> + __GNUC_PATCHLEVEL__)
>
> -/* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 */
> -#if GCC_VERSION < 40900
> -# error Sorry, your version of GCC is too old - please use 4.9 or newer.
> -#elif defined(CONFIG_ARM64) && GCC_VERSION < 50100
> -/*
> - * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293
> - * https://lore.kernel.org/r/20210107111841.GN1551@xxxxxxxxxxxxxxxxxxxxx
> - */
> -# error Sorry, your version of GCC is too old - please use 5.1 or newer.
> -#endif
> -
> /*
> * This macro obfuscates arithmetic on a variable address so that gcc
> * shouldn't recognize the original var, and make assumptions about it.
> diff --git a/init/Kconfig b/init/Kconfig
> index b77c60f8b963..8f04e5db2001 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -26,11 +26,11 @@ config CC_VERSION_TEXT
> and then every file will be rebuilt.
>
> config CC_IS_GCC
> - def_bool $(success,echo "$(CC_VERSION_TEXT)" | grep -q gcc)
> + def_bool $(success,test "$(cc-name)" = GCC)
>
> config GCC_VERSION
> int
> - default $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) if CC_IS_GCC
> + default $(cc-version) if CC_IS_GCC
> default 0
>
> config LD_VERSION
> @@ -38,14 +38,15 @@ config LD_VERSION
> default $(shell,$(LD) --version | $(srctree)/scripts/ld-version.sh)
>
> config CC_IS_CLANG
> - def_bool $(success,echo "$(CC_VERSION_TEXT)" | grep -q clang)
> + def_bool $(success,test "$(cc-name)" = Clang)
>
> config LD_IS_LLD
> def_bool $(success,$(LD) -v | head -n 1 | grep -q LLD)
>
> config CLANG_VERSION
> int
> - default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
> + default $(cc-version) if CC_IS_CLANG
> + default 0
>
> config LLD_VERSION
> int
> diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
> index a5fe72c504ff..0228cb9c74aa 100644
> --- a/scripts/Kconfig.include
> +++ b/scripts/Kconfig.include
> @@ -39,6 +39,12 @@ as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) -c -x assembler
> $(error-if,$(failure,command -v $(CC)),compiler '$(CC)' not found)
> $(error-if,$(failure,command -v $(LD)),linker '$(LD)' not found)
>
> +# 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)
> +
> # Fail if the linker is gold as it's not capable of linking the kernel proper
> $(error-if,$(success, $(LD) -v | grep -q gold), gold linker '$(LD)' not supported)
>
> diff --git a/scripts/cc-version.sh b/scripts/cc-version.sh
> new file mode 100755
> index 000000000000..d1edbe4d140c
> --- /dev/null
> +++ b/scripts/cc-version.sh
> @@ -0,0 +1,82 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Print the compiler name and its version in a 5 or 6-digit form.
> +# Also, perform the minimum version check.
> +
> +set -e
> +
> +# When you raise the compiler version, please update
> +# Documentation/process/changes.rst as well.
> +gcc_min_version=4.9.0
> +clang_min_version=10.0.1
> +icc_min_version=16.0.3 # temporary
> +
> +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293
> +# https://lore.kernel.org/r/20210107111841.GN1551@xxxxxxxxxxxxxxxxxxxxx
> +if [ "$SRCARCH" = arm64 ]; then
> + gcc_min_version=5.1.0
> +fi
> +
> +# print the compiler name and versions
> +get_compiler_info()
> +{
> + cat <<- EOF | "$@" -E -P -x c - 2>/dev/null
> + #if defined(__clang__)
> + Clang __clang_major__ __clang_minor__ __clang_patchlevel__
> + #elif defined(__INTEL_COMPILER)
> + ICC __INTEL_COMPILER __INTEL_COMPILER_UPDATE
> + #elif defined(__GNUC__)
> + GCC __GNUC__ __GNUC_MINOR__ __GNUC_PATCHLEVEL__
> + #else
> + unknown
> + #endif
> + EOF
> +}
> +
> +# convert the version string x.y.z to a canonical 5 or 6-digit form
> +get_canonical_version()
> +{
> + IFS=.
> + set -- $1
> + echo $((10000 * $1 + 100 * $2 + $3))
> +}
> +
> +# $@ instead of $1 because multiple words might be given e.g. CC="ccache gcc"
> +orig_args="$@"
> +set -- $(get_compiler_info "$@")
> +
> +name=$1
> +
> +case "$name" in
> +GCC)
> + version=$2.$3.$4
> + min_version=$gcc_min_version
> + ;;
> +Clang)
> + version=$2.$3.$4
> + min_version=$clang_min_version
> + ;;
> +ICC)
> + version=$(($2 / 100)).$(($2 % 100)).$3
> + min_version=$icc_min_version
> + ;;
> +*)
> + echo "$orig_args: unknown compiler" >&2
> + exit 1
> + ;;
> +esac
> +
> +cversion=$(get_canonical_version $version)
> +min_cversion=$(get_canonical_version $min_version)
> +
> +if [ "$cversion" -lt "$min_cversion" ]; then
> + echo >&2 "***"
> + echo >&2 "*** Compiler is too old."
> + echo >&2 "*** Your $name version: $version"
> + echo >&2 "*** Minimum $name version: $min_version"
> + echo >&2 "***"
> + exit 1
> +fi
> +
> +echo $name $cversion
> diff --git a/scripts/clang-version.sh b/scripts/clang-version.sh
> deleted file mode 100755
> index 6fabf0695761..000000000000
> --- a/scripts/clang-version.sh
> +++ /dev/null
> @@ -1,19 +0,0 @@
> -#!/bin/sh
> -# SPDX-License-Identifier: GPL-2.0
> -#
> -# clang-version clang-command
> -#
> -# Print the compiler version of `clang-command' in a 5 or 6-digit form
> -# such as `50001' for clang-5.0.1 etc.
> -
> -compiler="$*"
> -
> -if ! ( $compiler --version | grep -q clang) ; then
> - echo 0
> - exit 1
> -fi
> -
> -MAJOR=$(echo __clang_major__ | $compiler -E -x c - | tail -n 1)
> -MINOR=$(echo __clang_minor__ | $compiler -E -x c - | tail -n 1)
> -PATCHLEVEL=$(echo __clang_patchlevel__ | $compiler -E -x c - | tail -n 1)
> -printf "%d%02d%02d\\n" $MAJOR $MINOR $PATCHLEVEL
> diff --git a/scripts/gcc-version.sh b/scripts/gcc-version.sh
> deleted file mode 100755
> index ae353432539b..000000000000
> --- a/scripts/gcc-version.sh
> +++ /dev/null
> @@ -1,20 +0,0 @@
> -#!/bin/sh
> -# SPDX-License-Identifier: GPL-2.0
> -#
> -# gcc-version gcc-command
> -#
> -# Print the gcc version of `gcc-command' in a 5 or 6-digit form
> -# such as `29503' for gcc-2.95.3, `30301' for gcc-3.3.1, etc.
> -
> -compiler="$*"
> -
> -if [ ${#compiler} -eq 0 ]; then
> - echo "Error: No compiler specified." >&2
> - printf "Usage:\n\t$0 <gcc-command>\n" >&2
> - exit 1
> -fi
> -
> -MAJOR=$(echo __GNUC__ | $compiler -E -x c - | tail -n 1)
> -MINOR=$(echo __GNUC_MINOR__ | $compiler -E -x c - | tail -n 1)
> -PATCHLEVEL=$(echo __GNUC_PATCHLEVEL__ | $compiler -E -x c - | tail -n 1)
> -printf "%d%02d%02d\\n" $MAJOR $MINOR $PATCHLEVEL
> --
> 2.27.0
>
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--
Best Regards
Masahiro Yamada

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