# git rev-parse -q --verify 06513ddaf77b8f49ef8540c92d92c9ef0ad49426^{commit}
06513ddaf77b8f49ef8540c92d92c9ef0ad49426
already have revision, skipping fetch
# git checkout -q -f -B kisskb 06513ddaf77b8f49ef8540c92d92c9ef0ad49426
# git clean -qxdf
# < git log -1
# commit 06513ddaf77b8f49ef8540c92d92c9ef0ad49426
# Author: Masahiro Yamada <masahiroy@kernel.org>
# Date:   Sun Nov 10 10:34:39 2024 +0900
# 
#     kbuild: allow to start building external modules in any directory
#     
#     Unless an explicit O= option is provided, external module builds must
#     start from the kernel directory.
#     
#     This can be achieved by using the -C option:
#     
#       $ make -C /path/to/kernel M=/path/to/external/module
#     
#     This commit allows starting external module builds from any directory,
#     so you can also do the following:
#     
#       $ make -f /path/to/kernel/Makefile M=/path/to/external/module
#     
#     The key difference is that the -C option changes the working directory
#     and parses the Makefile located there, while the -f option only
#     specifies the Makefile to use.
#     
#     As shown in the examples in Documentation/kbuild/modules.rst, external
#     modules usually have a wrapper Makefile that allows you to build them
#     without specifying any make arguments. The Makefile typically contains
#     a rule as follows:
#     
#         KDIR ?= /path/to/kernel
#         default:
#                 $(MAKE) -C $(KDIR) M=$(CURDIR) $(MAKECMDGOALS)
#     
#     The log will appear as follows:
#     
#         $ make
#         make -C /path/to/kernel M=/path/to/external/module
#         make[1]: Entering directory '/path/to/kernel'
#         make[2]: Entering directory '/path/to/external/module'
#           CC [M]  helloworld.o
#           MODPOST Module.symvers
#           CC [M]  helloworld.mod.o
#           CC [M]  .module-common.o
#           LD [M]  helloworld.ko
#         make[2]: Leaving directory '/path/to/external/module'
#         make[1]: Leaving directory '/path/to/kernel'
#     
#     This changes the working directory twice because the -C option first
#     switches to the kernel directory, and then Kbuild internally recurses
#     back to the external module directory.
#     
#     With this commit, the wrapper Makefile can directly include the kernel
#     Makefile:
#     
#         KDIR ?= /path/to/kernel
#         export KBUILD_EXTMOD := $(realpath $(dir $(lastword $(MAKEFILE_LIST))))
#         include $(KDIR)/Makefile
#     
#     This avoids unnecessary sub-make invocations:
#     
#         $ make
#           CC [M]  helloworld.o
#           MODPOST Module.symvers
#           CC [M]  helloworld.mod.o
#           CC [M]  .module-common.o
#           LD [M]  helloworld.ko
#     
#     Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
#     Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
# < /opt/cross/kisskb/korg/gcc-13.1.0-nolibc/aarch64-linux/bin/aarch64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-13.1.0-nolibc/aarch64-linux/bin/aarch64-linux-ld --version
# < git log --format=%s --max-count=1 06513ddaf77b8f49ef8540c92d92c9ef0ad49426
# make -s -j 160 ARCH=arm64 O=/kisskb/build/kbuild_defconfig_arm64-gcc13 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-13.1.0-nolibc/aarch64-linux/bin/aarch64-linux-  defconfig
# < make -s -j 160 ARCH=arm64 O=/kisskb/build/kbuild_defconfig_arm64-gcc13 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-13.1.0-nolibc/aarch64-linux/bin/aarch64-linux-  help
# make -s -j 160 ARCH=arm64 O=/kisskb/build/kbuild_defconfig_arm64-gcc13 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-13.1.0-nolibc/aarch64-linux/bin/aarch64-linux-  olddefconfig
# make -s -j 160 ARCH=arm64 O=/kisskb/build/kbuild_defconfig_arm64-gcc13 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-13.1.0-nolibc/aarch64-linux/bin/aarch64-linux-  
Completed OK
# rm -rf /kisskb/build/kbuild_defconfig_arm64-gcc13
# Build took: 0:04:23.847902