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13b25489b6
Currently, Kbuild always operates in the output directory of the kernel,
even when building external modules. This increases the risk of external
module Makefiles attempting to write to the kernel directory.
This commit switches the working directory to the external module
directory, allowing the removal of the $(KBUILD_EXTMOD)/ prefix from
some build artifacts.
The command for building external modules maintains backward
compatibility, but Makefiles that rely on working in the kernel
directory may break. In such cases, $(objtree) and $(srctree) should
be used to refer to the output and source directories of the kernel.
The appearance of the build log will change as follows:
[Before]
$ make -C /path/to/my/linux M=/path/to/my/externel/module
make: Entering directory '/path/to/my/linux'
CC [M] /path/to/my/externel/module/helloworld.o
MODPOST /path/to/my/externel/module/Module.symvers
CC [M] /path/to/my/externel/module/helloworld.mod.o
CC [M] /path/to/my/externel/module/.module-common.o
LD [M] /path/to/my/externel/module/helloworld.ko
make: Leaving directory '/path/to/my/linux'
[After]
$ make -C /path/to/my/linux M=/path/to/my/externel/module
make: Entering directory '/path/to/my/linux'
make[1]: Entering directory '/path/to/my/externel/module'
CC [M] helloworld.o
MODPOST Module.symvers
CC [M] helloworld.mod.o
CC [M] .module-common.o
LD [M] helloworld.ko
make[1]: Leaving directory '/path/to/my/externel/module'
make: Leaving directory '/path/to/my/linux'
Printing "Entering directory" twice is cumbersome. This will be
addressed later.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>
86 lines
2.6 KiB
Bash
Executable file
86 lines
2.6 KiB
Bash
Executable file
#!/bin/sh
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# SPDX-License-Identifier: GPL-2.0-only
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set -eu
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destdir=${1}
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is_enabled() {
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grep -q "^$1=y" include/config/auto.conf
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}
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find_in_scripts() {
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find scripts \
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\( -name atomic -o -name dtc -o -name kconfig -o -name package \) -prune -o \
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! -name unifdef -a ! -name mk_elfconfig -a \( -type f -o -type l \) -print
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}
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mkdir -p "${destdir}"
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(
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cd "${srctree}"
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echo Makefile
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find "arch/${SRCARCH}" -maxdepth 1 -name 'Makefile*'
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find "arch/${SRCARCH}" -name generated -prune -o -name include -type d -print
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find "arch/${SRCARCH}" -name Kbuild.platforms -o -name Platform
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find include \( -name config -o -name generated \) -prune -o \( -type f -o -type l \) -print
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find_in_scripts
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) | tar -c -f - -C "${srctree}" -T - | tar -xf - -C "${destdir}"
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{
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if is_enabled CONFIG_OBJTOOL; then
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echo tools/objtool/objtool
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fi
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echo Module.symvers
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echo "arch/${SRCARCH}/include/generated"
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echo include/config/auto.conf
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echo include/config/kernel.release
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echo include/generated
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find_in_scripts
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if is_enabled CONFIG_GCC_PLUGINS; then
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find scripts/gcc-plugins -name '*.so'
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fi
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} | tar -c -f - -T - | tar -xf - -C "${destdir}"
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# When ${CC} and ${HOSTCC} differ, rebuild host programs using ${CC}.
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#
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# This caters to host programs that participate in Kbuild. objtool and
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# resolve_btfids are out of scope.
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if [ "${CC}" != "${HOSTCC}" ]; then
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echo "Rebuilding host programs with ${CC}..."
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# This leverages external module building.
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# - Clear sub_make_done to allow the top-level Makefile to redo sub-make.
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# - Filter out --no-print-directory to print "Entering directory" logs
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# when Make changes the working directory.
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unset sub_make_done
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MAKEFLAGS=$(echo "${MAKEFLAGS}" | sed s/--no-print-directory//)
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cat <<-'EOF' > "${destdir}/Kbuild"
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subdir-y := scripts
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EOF
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# HOSTCXX is not overridden. The C++ compiler is used to build:
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# - scripts/kconfig/qconf, which is unneeded for external module builds
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# - GCC plugins, which will not work on the installed system even after
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# being rebuilt.
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#
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# Use the single-target build to avoid the modpost invocation, which
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# would overwrite Module.symvers.
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"${MAKE}" HOSTCC="${CC}" KBUILD_EXTMOD="${destdir}" scripts/
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cat <<-'EOF' > "${destdir}/scripts/Kbuild"
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subdir-y := basic
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hostprogs-always-y := mod/modpost
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mod/modpost-objs := $(addprefix mod/, modpost.o file2alias.o sumversion.o symsearch.o)
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EOF
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# Run once again to rebuild scripts/basic/ and scripts/mod/modpost.
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"${MAKE}" HOSTCC="${CC}" KBUILD_EXTMOD="${destdir}" scripts/
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rm -f "${destdir}/Kbuild" "${destdir}/scripts/Kbuild"
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fi
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find "${destdir}" \( -name '.*.cmd' -o -name '*.o' \) -delete
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