linux/scripts/package/install-extmod-build, branch v6.18

kbuild: install-extmod-build: Fix when given dir outside the build dir

2025-10-25T20:59:20Z

Commit b5e395653546 ("kbuild: install-extmod-build: Fix build when specifying KBUILD_OUTPUT") tried to address the "build" variable expecting a relative path by using `realpath --relative-base=.`, but this only works when the given directory is below the current directory. `realpath --relative-to=.` will return a relative path in all cases. Fixes: b5e395653546 ("kbuild: install-extmod-build: Fix build when specifying KBUILD_OUTPUT") Signed-off-by: James Le Cuirot Reviewed-by: Nicolas Schier Link: https://patch.msgid.link/20251016091417.9985-1-chewi@gentoo.org Signed-off-by: Nathan Chancellor

kbuild: install-extmod-build: Fix build when specifying KBUILD_OUTPUT

2025-03-06T11:32:30Z

Since commit 5f73e7d0386d ("kbuild: refactor cross-compiling linux-headers package"), the linux-headers pacman package fails to build when "O=" is set. The build system complains: /mnt/chroot/linux/scripts/Makefile.build:41: mnt/chroots/linux-mainline/pacman/linux-upstream/pkg/linux-upstream-headers/usr//lib/modules/6.14.0-rc3-00350-g771dba31fffc/build/scripts/Makefile: No such file or directory This is because the "srcroot" variable is set to "." and the "build" variable is set to the absolute path. This makes the "src" variables point to wrong directory. Change the "build" variable to a relative path to "." to fix build. Fixes: 5f73e7d0386d ("kbuild: refactor cross-compiling linux-headers package") Signed-off-by: Inochi Amaoto Signed-off-by: Masahiro Yamada

kbuild: fix linux-headers package build when $(CC) cannot link userspace

2025-02-15T13:40:52Z

Since commit 5f73e7d0386d ("kbuild: refactor cross-compiling linux-headers package"), the linux-headers Debian package fails to build when $(CC) cannot build userspace applications, for example, when using toolchains installed by the 0day bot. The host programs in the linux-headers package should be rebuilt using the disto's cross-compiler, ${DEB_HOST_GNU_TYPE}-gcc instead of $(CC). Hence, the variable 'CC' must be expanded in this shell script instead of in the top-level Makefile. Commit f354fc88a72a ("kbuild: install-extmod-build: add missing quotation marks for CC variable") was not a correct fix because CC="ccache gcc" should be unrelated when rebuilding userspace tools. Fixes: 5f73e7d0386d ("kbuild: refactor cross-compiling linux-headers package") Reported-by: Jeff Johnson Closes: https://lore.kernel.org/linux-kbuild/CAK7LNARb3xO3ptBWOMpwKcyf3=zkfhMey5H2KnB1dOmUwM79dA@mail.gmail.com/T/#t Signed-off-by: Masahiro Yamada Tested-by: Jeff Johnson

kbuild: install-extmod-build: add missing quotation marks for CC variable

2025-02-07T18:37:57Z

While attempting to build a Debian packages with CC="ccache gcc", I saw the following error as builddeb builds linux-headers-$KERNELVERSION: make HOSTCC=ccache gcc VPATH= srcroot=. -f ./scripts/Makefile.build obj=debian/linux-headers-6.14.0-rc1/usr/src/linux-headers-6.14.0-rc1/scripts make[6]: *** No rule to make target 'gcc'. Stop. Upon investigation, it seems that one instance of $(CC) variable reference in ./scripts/package/install-extmod-build was missing quotation marks, causing the above error. Add the missing quotation marks around $(CC) to fix build. Fixes: 5f73e7d0386d ("kbuild: refactor cross-compiling linux-headers package") Co-developed-by: Mingcong Bai Signed-off-by: Mingcong Bai Tested-by: WangYuli Signed-off-by: WangYuli Signed-off-by: Masahiro Yamada

kbuild: refactor cross-compiling linux-headers package

2025-01-10T14:01:21Z

Since commit 13b25489b6f8 ("kbuild: change working directory to external module directory with M="), when cross-building host programs for the linux-headers package, the "Entering directory" and "Leaving directory" messages appear multiple times, and each object path shown is relative to the working directory. This makes it difficult to track which objects are being rebuilt. In hindsight, using the external module build (M=) was not a good idea. This commit simplifies the script by leveraging the run-command target, resulting in a cleaner build log again. [Before] $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg [ snip ] Rebuilding host programs with aarch64-linux-gnu-gcc... make[5]: Entering directory '/home/masahiro/linux' make[6]: Entering directory '/home/masahiro/linux/debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+' HOSTCC scripts/kallsyms HOSTCC scripts/sorttable HOSTCC scripts/asn1_compiler make[6]: Leaving directory '/home/masahiro/linux/debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+' make[5]: Leaving directory '/home/masahiro/linux' make[5]: Entering directory '/home/masahiro/linux' make[6]: Entering directory '/home/masahiro/linux/debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+' HOSTCC scripts/basic/fixdep HOSTCC scripts/mod/modpost.o HOSTCC scripts/mod/file2alias.o HOSTCC scripts/mod/sumversion.o HOSTCC scripts/mod/symsearch.o HOSTLD scripts/mod/modpost make[6]: Leaving directory '/home/masahiro/linux/debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+' make[5]: Leaving directory '/home/masahiro/linux' [After] $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg [ snip ] HOSTCC debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+/scripts/basic/fixdep HOSTCC debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+/scripts/kallsyms HOSTCC debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+/scripts/sorttable HOSTCC debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+/scripts/asn1_compiler HOSTCC debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+/scripts/mod/modpost.o HOSTCC debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+/scripts/mod/file2alias.o HOSTCC debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+/scripts/mod/sumversion.o HOSTCC debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+/scripts/mod/symsearch.o HOSTLD debian/linux-headers-6.13.0-rc1+/usr/src/linux-headers-6.13.0-rc1+/scripts/mod/modpost Signed-off-by: Masahiro Yamada

kbuild: deb-pkg: fix build error with O=

2024-12-08T08:11:34Z

Since commit 13b25489b6f8 ("kbuild: change working directory to external module directory with M="), the Debian package build fails if a relative path is specified with the O= option. $ make O=build bindeb-pkg [ snip ] dpkg-deb: building package 'linux-image-6.13.0-rc1' in '../linux-image-6.13.0-rc1_6.13.0-rc1-6_amd64.deb'. Rebuilding host programs with x86_64-linux-gnu-gcc... make[6]: Entering directory '/home/masahiro/linux/build' /home/masahiro/linux/Makefile:190: *** specified kernel directory "build" does not exist. Stop. This occurs because the sub_make_done flag is cleared, even though the working directory is already in the output directory. Passing KBUILD_OUTPUT=. resolves the issue. Fixes: 13b25489b6f8 ("kbuild: change working directory to external module directory with M=") Reported-by: Charlie Jenkins Closes: https://lore.kernel.org/all/Z1DnP-GJcfseyrM3@ghost/ Tested-by: Charlie Jenkins Reviewed-by: Charlie Jenkins Signed-off-by: Masahiro Yamada

kbuild: change working directory to external module directory with M=

2024-11-27T23:10:23Z

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 Reviewed-by: Nicolas Schier

kbuild: deb-pkg: add pkg.linux-upstream.nokernelheaders build profile

2024-10-31T12:41:02Z

Since commit f1d87664b82a ("kbuild: cross-compile linux-headers package when possible"), 'make bindeb-pkg' may attempt to cross-compile the linux-headers package, but it fails under certain circumstances. For example, when CONFIG_MODULE_SIG_FORMAT is enabled on Debian, the following command fails: $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg [ snip ] Rebuilding host programs with aarch64-linux-gnu-gcc... HOSTCC debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/kallsyms HOSTCC debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sorttable HOSTCC debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/asn1_compiler HOSTCC debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sign-file In file included from /usr/include/openssl/opensslv.h:109, from debian/linux-headers-6.12.0-rc4/usr/src/linux-headers-6.12.0-rc4/scripts/sign-file.c:25: /usr/include/openssl/macros.h:14:10: fatal error: openssl/opensslconf.h: No such file or directory 14 | #include | ^~~~~~~~~~~~~~~~~~~~~~~ compilation terminated. This commit adds a new profile, pkg.linux-upstream.nokernelheaders, to guard the linux-headers package. There are two options to fix the above issue. Option 1: Set the pkg.linux-upstream.nokernelheaders build profile $ DEB_BUILD_PROFILES=pkg.linux-upstream.nokernelheaders \ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg This skips the building of the linux-headers package. Option 2: Install the necessary build dependencies If you want to cross-compile the linux-headers package, you need to install additional packages. For example, on Debian, the packages necessary for cross-compiling it to arm64 can be installed with the following commands: # dpkg --add-architecture arm64 # apt update # apt install gcc-aarch64-linux-gnu libssl-dev:arm64 Fixes: f1d87664b82a ("kbuild: cross-compile linux-headers package when possible") Reported-by: Ron Economos Closes: https://lore.kernel.org/all/b3d4f49e-7ddb-29ba-0967-689232329b53@w6rz.net/ Signed-off-by: Masahiro Yamada Tested-by: Ron Economos Reviewed-by: Nicolas Schier

kbuild: cross-compile linux-headers package when possible

2024-09-01T11:33:33Z

A long standing issue in the upstream kernel packaging is that the linux-headers package is not cross-compiled. For example, you can cross-build Debian packages for arm64 by running the following command: $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bindeb-pkg However, the generated linux-headers-*_arm64.deb is useless because the host programs in it were built for your build machine architecture (likely x86), not arm64. The Debian kernel maintains its own Makefiles to cross-compile host tools without relying on Kbuild. [1] Instead of adding such full custom Makefiles, this commit adds a small piece of code to cross-compile host programs located under the scripts/ directory. A straightforward solution is to pass HOSTCC=${CROSS_COMPILE}gcc, but it would also cross-compile scripts/basic/fixdep, which needs to be native to process the if_changed_dep macro. (This approach may work under some circumstances; you can execute foreign architecture programs with the help of binfmt_misc because Debian systems enable CONFIG_BINFMT_MISC, but it would require installing QEMU and libc for that architecture.) A trick is to use the external module build (KBUILD_EXTMOD=), which does not rebuild scripts/basic/fixdep. ${CC} needs to be able to link userspace programs (CONFIG_CC_CAN_LINK=y). There are known limitations: - GCC plugins It would possible to rebuild GCC plugins for the target architecture by passing HOSTCXX=${CROSS_COMPILE}g++ with necessary packages installed, but gcc on the installed system emits "cc1: error: incompatible gcc/plugin versions". - objtool and resolve_btfids These are built by the tools build system. They are not covered by the current solution. The resulting linux-headers package is broken if CONFIG_OBJTOOL or CONFIG_DEBUG_INFO_BTF is enabled. I only tested this with Debian, but it should work for other package systems as well. [1]: https://salsa.debian.org/kernel-team/linux/-/blob/debian/6.9.9-1/debian/rules.real#L586 Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier

kbuild: slim down package for building external modules

2024-09-01T11:33:33Z

Exclude directories and files unnecessary for building external modules: - include/config/ (except include/config/{auto.conf,kernel.release}) - scripts/atomic/ - scripts/dtc/ - scripts/kconfig/ - scripts/mod/mk_elfconfig - scripts/package/ - scripts/unifdef - .config - *.o - .*.cmd Avoid copying files twice for the following directories: - include/generated/ - arch/*/include/generated/ Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier