Re: [PATCH v3 1/3] scripts: kconfig: merge_config.sh: refactor from shell/sed/grep to awk

[Nathan Chancellor <nathan@kernel.org>]

On Mon, Mar 09, 2026 at 05:38:58PM +0100, Andreas Larsson wrote:
> On 2026-01-22 11:57, Mikko Rapeli wrote:
> > From: Anders Roxell <anders.roxell@linaro.org>
> > 
> > merge_config.sh shell/sed/grep loop scales poorly and is slow.
> > With Yocto genericarm64 kernel and around 190 config fragments
> > the script takes more than 20 minutes to run on a fast build machine.
> > Re-implementation with awk does the same job in 10 seconds.
> > Using awk since it is likely available in the build environments
> > and using perl, python etc would introduce more complex runtime
> > dependencies. awk is good enough and lot better than shell/sed/grep.
> > 
> > Output stays the same but changed execution time means that
> > parallel job output may be ordered differently.
> > 
> > Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
> > Signed-off-by: Mikko Rapeli <mikko.rapeli@linaro.org>
> > ---
> >  scripts/kconfig/merge_config.sh | 168 ++++++++++++++++++++++++--------
> >  1 file changed, 128 insertions(+), 40 deletions(-)
> 
> Hi,
> 
> Commit 5fa9b82cbcfc ("scripts: kconfig: merge_config.sh: refactor from
> shell/sed/grep to awk") breaks merge_config.sh for me:
> 
> ---------->%----------
> $ make tiny.config
>   HOSTCC  scripts/basic/fixdep
>   HOSTCC  scripts/kconfig/conf.o
>   HOSTCC  scripts/kconfig/confdata.o
>   HOSTCC  scripts/kconfig/expr.o
>   LEX     scripts/kconfig/lexer.lex.c
>   YACC    scripts/kconfig/parser.tab.[ch]
>   HOSTCC  scripts/kconfig/lexer.lex.o
>   HOSTCC  scripts/kconfig/menu.o
>   HOSTCC  scripts/kconfig/parser.tab.o
>   HOSTCC  scripts/kconfig/preprocess.o
>   HOSTCC  scripts/kconfig/symbol.o
>   HOSTCC  scripts/kconfig/util.o
>   HOSTLD  scripts/kconfig/conf
> The base file '.config' does not exist. Creating one...
> Using .config as base
> Merging ./kernel/configs/tiny.config
> awk: cannot open ./.tmp.config.U9SROCKTBj.new (No such file or directory)
> mv: cannot stat './.tmp.config.U9SROCKTBj.new': No such file or directory
> make[2]: *** [scripts/kconfig/Makefile:112: tiny.config] Error 1
> make[1]: *** [<kernel-source-top-dir>/Makefile:744: tiny.config] Error 2
> make: *** [Makefile:248: __sub-make] Error 2
> ---------->%----------
> 
> with this underlying call to merge_config.sh, an empty .config and where
> my awk is GNU Awk 5.1.0:
> 
> ---------->%----------
> $ make tiny.config V=1
> make --no-print-directory -C <kernel-source-top-dir> \
> -f <kernel-source-top-dir>/Makefile tiny.config
> make -f ./scripts/Makefile.build obj=scripts/basic
> make -f ./scripts/Makefile.build obj=scripts/kconfig tiny.config
> # cmd_merge_fragments tiny.config
>   ./scripts/kconfig/merge_config.sh -m .config ./kernel/configs/tiny.config ./arch/x86/configs/tiny.config
> ...
> 
> $ awk --version
> GNU Awk 5.1.0, API: 3.0 (GNU MPFR 4.1.0, GNU MP 6.2.1)
> ---------->%----------
> 
> At 5fa9b82cbcfc~ things works as expected.

Hmmm, not sure how I have not seen this error myself since I test
tiny.config but I can reproduce with a clean output directory. Something
like this seems like a simple fix but the only instances of ARGV[3] in
the awk script that I can see use '>>', which should create the file if
it does not exist. Mikko, any ideas?

diff --git a/scripts/kconfig/merge_config.sh b/scripts/kconfig/merge_config.sh
index 735e1de450c6..070ecae87a1c 100755
--- a/scripts/kconfig/merge_config.sh
+++ b/scripts/kconfig/merge_config.sh
@@ -123,6 +123,7 @@ fi
 MERGE_LIST=$*
 
 TMP_FILE=$(mktemp ./.tmp.config.XXXXXXXXXX)
+touch "$TMP_FILE.new"
 
 echo "Using $INITFILE as base"