linux/init
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
..
calibrate.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
do_mounts_initrd.c Merge branch 'hch.init_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 09:40:34 -07:00
do_mounts_rd.c init: add an init_unlink helper 2020-07-31 08:17:52 +02:00
do_mounts.c block: merge struct block_device and struct hd_struct 2020-12-01 14:53:40 -07:00
do_mounts.h init: add an init_mknod helper 2020-07-31 08:17:54 +02:00
init_task.c fgraph: Initialize tracing_graph_pause at task creation 2021-01-29 15:07:32 -05:00
initramfs.c initramfs: fix clang build failure 2020-12-11 14:02:14 -08:00
Kconfig kbuild: check the minimum compiler version in Kconfig 2021-02-16 12:01:32 +09:00
main.c init/gcov: allow CONFIG_CONSTRUCTORS on UML to fix module gcov 2021-02-05 11:03:47 -08:00
Makefile md: move the early init autodetect code to drivers/md/ 2020-07-16 15:34:47 +02:00
noinitramfs.c init: add an init_mknod helper 2020-07-31 08:17:54 +02:00
version.c uts: Use generic ns_common::count 2020-08-19 14:13:20 +02:00