Re: [PATCH v2] kbuild: modules-cpio-pkg: Respect INSTALL_MOD_PATH

[Nathan Chancellor <nathan@kernel.org>]

On Wed, Mar 25, 2026 at 03:57:25PM +0100, Janne Grunau wrote:
> The modules-cpio-pkg target added in commit 2a9c8c0b59d3 ("kbuild: add
> target to build a cpio containing modules") is incompatible with
> initramfs with merged /lib and /usr/lib directories [1]. "/lib" cannot
> be a link and directory at the same time.
> Respect a non-empty INSTALL_MOD_PATH in the modules-cpio-pkg target so
> that `make INSTALL_MOD_PATH=/usr modules-cpio-pkg` results in the same
> module install location as `make INSTALL_MOD_PATH=/usr modules_install`.
> 
> Tested with Fedora distribution initramfs produced by dracut.
> 
> Link: https://systemd.io/THE_CASE_FOR_THE_USR_MERGE/ [1]
> Fixes: 2a9c8c0b59d3 ("kbuild: add target to build a cpio containing modules")
> Cc: stable@vger.kernel.org
> Reviewed-by: Simon Glass <sjg@chromium.org>
> Signed-off-by: Janne Grunau <j@jannau.net>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
> Hej,
> 
> this patch allows to produce modules-cpio initramfs which are compatible
> with initramfs with merged /lib and /usr/lib (/lib as symlink to
> /usr/lib). I expect initramfs of distributions with merged /usr to have
> a merged /usr as well. This is at least true for Fedora initramfs built
> with dracut.
> 
> Janne
> ---
> Changes in v2:
> - drop pointless avoidance of repeated slashes
> - comment the changed Makefile rule
> - break long modles-cpio-pkg help text to 2 lines
> - imported Simon's Rb:
> - add fixes tag for commit 2a9c8c0b59d3 ("kbuild: add target to build a cpio containing modules")
> - Link to v1: https://lore.kernel.org/r/20260320-kbuild-modules-cpio-pkg-usr-merge-v1-1-cee1ad1bb7cb@jannau.net
> ---
>  scripts/Makefile.package | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/Makefile.package b/scripts/Makefile.package
> index 0ec946f9b905f74f8698d8d6967d22f5b76f64e0..c19b88b346d0632cc99e74617d79b07d81d48635 100644
> --- a/scripts/Makefile.package
> +++ b/scripts/Makefile.package
> @@ -195,7 +195,8 @@ tar%-pkg: linux-$(KERNELRELEASE)-$(ARCH).tar.% FORCE
>  .tmp_modules_cpio: FORCE
>  	$(Q)$(MAKE) -f $(srctree)/Makefile
>  	$(Q)rm -rf $@
> -	$(Q)$(MAKE) -f $(srctree)/Makefile INSTALL_MOD_PATH=$@ modules_install
> +	# Prepend INSTALL_MOD_PATH inside the staging dir
> +	$(Q)$(MAKE) -f $(srctree)/Makefile INSTALL_MOD_PATH=$@/$(INSTALL_MOD_PATH) modules_install
>  
>  quiet_cmd_cpio = CPIO    $@
>        cmd_cpio = $(CONFIG_SHELL) $(srctree)/usr/gen_initramfs.sh -o $@ $<
> @@ -264,6 +265,7 @@ help:
>  	@echo '  tarxz-pkg           - Build the kernel as a xz compressed tarball'
>  	@echo '  tarzst-pkg          - Build the kernel as a zstd compressed tarball'
>  	@echo '  modules-cpio-pkg    - Build the kernel modules as cpio archive'
> +	@echo '                        (uses INSTALL_MOD_PATH inside the archive)'
>  	@echo '  perf-tar-src-pkg    - Build the perf source tarball with no compression'
>  	@echo '  perf-targz-src-pkg  - Build the perf source tarball with gzip compression'
>  	@echo '  perf-tarbz2-src-pkg - Build the perf source tarball with bz2 compression'
> 
> ---
> base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
> change-id: 20260320-kbuild-modules-cpio-pkg-usr-merge-4266a460282c
> 
> Best regards,
> -- 
> Janne Grunau <j@jannau.net>
>