On Thu, Dec 05, 2024 at 11:48:08AM +0900, Masahiro Yamada wrote: > On Thu, Dec 5, 2024 at 8:35 AM Charlie Jenkins <charlie@xxxxxxxxxxxx> wrote: > > > > On Sun, Nov 10, 2024 at 10:34:33AM +0900, Masahiro Yamada wrote: > > > 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. > > > > This change has caused O=<relative directory> to fail. > > > > For example: > > > > make O=build defconfig > > make -j$(nproc) V=1 O=build bindeb-pkg > > > > outputs: > > > > make ARCH=x86 KERNELRELEASE=6.13.0-rc1 KBUILD_BUILD_VERSION=3 run-command KBUILD_RUN_COMMAND='+$(srctree)/scripts/package/builddeb linux-libc-dev' > > dh_installchangelogs -plinux-image-6.13.0-rc1 > > ../scripts/package/builddeb linux-headers-6.13.0-rc1 > > dh_compress -plinux-image-6.13.0-rc1 > > dh_fixperms -plinux-image-6.13.0-rc1 > > dh_gencontrol -plinux-image-6.13.0-rc1 -- -fdebian/image.files > > Rebuilding host programs with x86_64-linux-gnu-gcc... > > make[6]: Entering directory '/scratch/kernels/linux/build' > > /scratch/kernels/linux/Makefile:190: *** specified kernel directory "build" does not exist. Stop. > > > > It is stepping into this directory and then trying to find the directory > > it just stepped into so $(realpath $(KBUILD_OUTPUT)) returns an empty > > string. > > > > Using an absolute directory resolves this problem, but I believe it > > shouldn't be necessary. > > > Agree. > > I will apply the following fixup unless I have a better idea. > > > > > diff --git a/scripts/package/install-extmod-build > b/scripts/package/install-extmod-build > index 64d958ee45f3..85af1573db31 100755 > --- a/scripts/package/install-extmod-build > +++ b/scripts/package/install-extmod-build > @@ -69,7 +69,7 @@ if [ "${CC}" != "${HOSTCC}" ]; then > # > # Use the single-target build to avoid the modpost invocation, which > # would overwrite Module.symvers. > - "${MAKE}" HOSTCC="${CC}" KBUILD_EXTMOD="${destdir}" scripts/ > + "${MAKE}" O=. HOSTCC="${CC}" KBUILD_EXTMOD="${destdir}" scripts/ > > cat <<-'EOF' > "${destdir}/scripts/Kbuild" > subdir-y := basic > @@ -78,7 +78,7 @@ if [ "${CC}" != "${HOSTCC}" ]; then > EOF > > # Run once again to rebuild scripts/basic/ and scripts/mod/modpost. > - "${MAKE}" HOSTCC="${CC}" KBUILD_EXTMOD="${destdir}" scripts/ > + "${MAKE}" O=. HOSTCC="${CC}" KBUILD_EXTMOD="${destdir}" scripts/ > > rm -f "${destdir}/Kbuild" "${destdir}/scripts/Kbuild" > fi > Looks fine to me :) If this is what you decide on, feel free to add my tags. Tested-by: Charlie Jenkins <charlie@xxxxxxxxxxxx> Reviewed-by: Charlie Jenkins <charlie@xxxxxxxxxxxx> > > > -- > Best Regards > Masahiro Yamada