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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Wed, 7 Jun 2023 14:34:52 +0900
Message-ID: <CAK7LNAQfLO5tueB2d6WsyWC=cLwiONo13+MLKFO0sSt57aTw-A@mail.gmail.com>
Subject: Re: [PATCH v2] initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP
To:     Benjamin Gray <bgray@linux.ibm.com>
Cc:     linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
        Andrew Donnellan <ajd@linux.ibm.com>
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On Tue, Jun 6, 2023 at 3:18=E2=80=AFPM Benjamin Gray <bgray@linux.ibm.com> =
wrote:
>
> gen_initramfs.sh has an internal dependency on KBUILD_BUILD_TIMESTAMP
> for generating file mtimes that is not exposed to make, so changing
> KBUILD_BUILD_TIMESTAMP will not trigger a rebuild of the archive.
>
> Declare the mtime date as a new parameter to gen_initramfs.sh to encode
> KBUILD_BUILD_TIMESTAMP in the shell command, thereby making make aware
> of the dependency.
>
> It will rebuild if KBUILD_BUILD_TIMESTAMP changes or is newly set/unset.
> It will _not_ rebuild if KBUILD_BUILD_TIMESTAMP is unset before and
> after. This should be fine for anyone who doesn't care about setting
> specific build times in the first place.
>
> Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
> Tested-by: Andrew Donnellan <ajd@linux.ibm.com>
> Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
>
> ---


Applied to linux-kbuild. Thanks.


> v2: Remove redundant comment, quote argument to shell script
> ---
>  usr/Makefile         |  1 +
>  usr/gen_initramfs.sh | 16 +++++++++-------
>  2 files changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/usr/Makefile b/usr/Makefile
> index 59d9e8b07a01..f8e1ad19e05c 100644
> --- a/usr/Makefile
> +++ b/usr/Makefile
> @@ -64,6 +64,7 @@ quiet_cmd_initfs =3D GEN     $@
>         $(CONFIG_SHELL) $< -o $@ -l $(obj)/.initramfs_data.cpio.d \
>         $(if $(CONFIG_INITRAMFS_ROOT_UID), -u $(CONFIG_INITRAMFS_ROOT_UID=
)) \
>         $(if $(CONFIG_INITRAMFS_ROOT_GID), -g $(CONFIG_INITRAMFS_ROOT_GID=
)) \
> +       $(if $(KBUILD_BUILD_TIMESTAMP), -d "$(KBUILD_BUILD_TIMESTAMP)") \
>         $(ramfs-input)
>
>  # We rebuild initramfs_data.cpio if:
> diff --git a/usr/gen_initramfs.sh b/usr/gen_initramfs.sh
> index 63476bb70b41..14b5782f961a 100755
> --- a/usr/gen_initramfs.sh
> +++ b/usr/gen_initramfs.sh
> @@ -23,6 +23,7 @@ $0 [-o <file>] [-l <dep_list>] [-u <uid>] [-g <gid>] {-=
d | <cpio_source>} ...
>         -g <gid>       Group ID to map to group ID 0 (root).
>                        <gid> is only meaningful if <cpio_source> is a
>                        directory.  "squash" forces all files to gid 0.
> +       -d <date>      Use date for all file mtime values
>         <cpio_source>  File list or directory for cpio archive.
>                        If <cpio_source> is a .cpio file it will be used
>                        as direct input to initramfs.
> @@ -190,6 +191,7 @@ prog=3D$0
>  root_uid=3D0
>  root_gid=3D0
>  dep_list=3D
> +timestamp=3D
>  cpio_list=3D$(mktemp ${TMPDIR:-/tmp}/cpiolist.XXXXXX)
>  output=3D"/dev/stdout"
>
> @@ -218,6 +220,13 @@ while [ $# -gt 0 ]; do
>                         [ "$root_gid" =3D "-1" ] && root_gid=3D$(id -g ||=
 echo 0)
>                         shift
>                         ;;
> +               "-d")   # date for file mtimes
> +                       timestamp=3D"$(date -d"$1" +%s || :)"
> +                       if test -n "$timestamp"; then
> +                               timestamp=3D"-t $timestamp"
> +                       fi
> +                       shift
> +                       ;;
>                 "-h")
>                         usage
>                         exit 0
> @@ -237,11 +246,4 @@ done
>
>  # If output_file is set we will generate cpio archive
>  # we are careful to delete tmp files
> -timestamp=3D
> -if test -n "$KBUILD_BUILD_TIMESTAMP"; then
> -       timestamp=3D"$(date -d"$KBUILD_BUILD_TIMESTAMP" +%s || :)"
> -       if test -n "$timestamp"; then
> -               timestamp=3D"-t $timestamp"
> -       fi
> -fi
>  usr/gen_init_cpio $timestamp $cpio_list > $output
> --
> 2.40.1
>


--=20
Best Regards
Masahiro Yamada