linux/scripts/cc-version.sh
Masahiro Yamada aec6c60a01 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: 87de84c914 ("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>
2021-02-16 12:01:32 +09:00

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#!/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 minimum 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@shell.armlinux.org.uk
if [ "$SRCARCH" = arm64 ]; then
gcc_min_version=5.1.0
fi
# Print the compiler name and some version components.
get_compiler_info()
{
cat <<- EOF | "$@" -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