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2df8220cc5
Kbuild builds init/built-in.a twice; first during the ordinary
directory descending, second from scripts/link-vmlinux.sh.
We do this because UTS_VERSION contains the build version and the
timestamp. We cannot update it during the normal directory traversal
since we do not yet know if we need to update vmlinux. UTS_VERSION is
temporarily calculated, but omitted from the update check. Otherwise,
vmlinux would be rebuilt every time.
When Kbuild results in running link-vmlinux.sh, it increments the
version number in the .version file and takes the timestamp at that
time to really fix UTS_VERSION.
However, updating the same file twice is a footgun. To avoid nasty
timestamp issues, all build artifacts that depend on init/built-in.a
are atomically generated in link-vmlinux.sh, where some of them do not
need rebuilding.
To fix this issue, this commit changes as follows:
[1] Split UTS_VERSION out to include/generated/utsversion.h from
include/generated/compile.h
include/generated/utsversion.h is generated just before the
vmlinux link. It is generated under include/generated/ because
some decompressors (s390, x86) use UTS_VERSION.
[2] Split init_uts_ns and linux_banner out to init/version-timestamp.c
from init/version.c
init_uts_ns and linux_banner contain UTS_VERSION. During the ordinary
directory descending, they are compiled with __weak and used to
determine if vmlinux needs relinking. Just before the vmlinux link,
they are compiled without __weak to embed the real version and
timestamp.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
34 lines
738 B
Bash
Executable file
34 lines
738 B
Bash
Executable file
#!/bin/sh
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# SPDX-License-Identifier: GPL-2.0
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UTS_MACHINE=$1
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CC_VERSION="$2"
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LD=$3
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# Do not expand names
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set -f
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# Fix the language to get consistent output
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LC_ALL=C
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export LC_ALL
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if test -z "$KBUILD_BUILD_USER"; then
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LINUX_COMPILE_BY=$(whoami | sed 's/\\/\\\\/')
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else
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LINUX_COMPILE_BY=$KBUILD_BUILD_USER
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fi
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if test -z "$KBUILD_BUILD_HOST"; then
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LINUX_COMPILE_HOST=`uname -n`
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else
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LINUX_COMPILE_HOST=$KBUILD_BUILD_HOST
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fi
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LD_VERSION=$($LD -v | head -n1 | sed 's/(compatible with [^)]*)//' \
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| sed 's/[[:space:]]*$//')
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cat <<EOF
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#define UTS_MACHINE "${UTS_MACHINE}"
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#define LINUX_COMPILE_BY "${LINUX_COMPILE_BY}"
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#define LINUX_COMPILE_HOST "${LINUX_COMPILE_HOST}"
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#define LINUX_COMPILER "${CC_VERSION}, ${LD_VERSION}"
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EOF
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