From: Sascha Hauer <s.hauer@pengutronix.de>

Add a new package target to build a cpio archive containing the kernel
modules. This is particularly useful to supplement an existing initramfs
with the kernel modules so that the root filesystem can be started with
all needed kernel modules without modifying it.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Co-developed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 scripts/Makefile.package | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/scripts/Makefile.package b/scripts/Makefile.package
index 74bcb9e7f7a4516473481468a0fcf700c3bead33..83bfcf7cb09fd2d69b97e0c19a2b99c728835e8d 100644
--- a/scripts/Makefile.package
+++ b/scripts/Makefile.package
@@ -189,6 +189,25 @@ tar-pkg: linux-$(KERNELRELEASE)-$(ARCH).tar
 tar%-pkg: linux-$(KERNELRELEASE)-$(ARCH).tar.% FORCE
 	@:
 
+# modules-cpio-pkg - generate an initramfs with the modules
+# ---------------------------------------------------------------------------
+
+.tmp_modules_cpio: FORCE
+	$(Q)$(MAKE) -f $(srctree)/Makefile
+	$(Q)rm -rf $@
+	$(Q)$(MAKE) -f $(srctree)/Makefile INSTALL_MOD_PATH=$@ modules_install
+
+quiet_cmd_cpio = CPIO    $@
+      cmd_cpio = $(CONFIG_SHELL) $(srctree)/usr/gen_initramfs.sh -o $@ $<
+
+modules-$(KERNELRELEASE)-$(ARCH).cpio: .tmp_modules_cpio
+	$(Q)$(MAKE) $(build)=usr usr/gen_init_cpio
+	$(call cmd,cpio)
+
+PHONY += modules-cpio-pkg
+modules-cpio-pkg: modules-$(KERNELRELEASE)-$(ARCH).cpio
+	@:
+
 # perf-tar*-src-pkg - generate a source tarball with perf source
 # ---------------------------------------------------------------------------
 
@@ -245,6 +264,7 @@ help:
 	@echo '  tarbz2-pkg          - Build the kernel as a bzip2 compressed tarball'
 	@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 '  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'

-- 
2.47.3

On Tue, Nov 25, 2025 at 02:18:20PM +0100, Ahmad Fatoum wrote:
> From: Sascha Hauer <s.hauer@pengutronix.de>
> 
> Add a new package target to build a cpio archive containing the kernel
> modules. This is particularly useful to supplement an existing initramfs
> with the kernel modules so that the root filesystem can be started with
> all needed kernel modules without modifying it.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> Reviewed-by: Simon Glass <sjg@chromium.org>
> Tested-by: Simon Glass <sjg@chromium.org>
> Co-developed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  scripts/Makefile.package | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/scripts/Makefile.package b/scripts/Makefile.package
> index 74bcb9e7f7a4516473481468a0fcf700c3bead33..83bfcf7cb09fd2d69b97e0c19a2b99c728835e8d 100644
> --- a/scripts/Makefile.package
> +++ b/scripts/Makefile.package
> @@ -189,6 +189,25 @@ tar-pkg: linux-$(KERNELRELEASE)-$(ARCH).tar
>  tar%-pkg: linux-$(KERNELRELEASE)-$(ARCH).tar.% FORCE
>  	@:
>  
> +# modules-cpio-pkg - generate an initramfs with the modules
> +# ---------------------------------------------------------------------------
> +
> +.tmp_modules_cpio: FORCE
> +	$(Q)$(MAKE) -f $(srctree)/Makefile
> +	$(Q)rm -rf $@
> +	$(Q)$(MAKE) -f $(srctree)/Makefile INSTALL_MOD_PATH=$@ modules_install

Do you know why '-f $(srctree)/Makefile' is necessary here?  As this
and the make call two lines above call common top-level targets, I do
not see the reason for explicitly adding the Makefile path.  Am I
missing something; or have you observed problems without '-f'?

> +
> +quiet_cmd_cpio = CPIO    $@
> +      cmd_cpio = $(CONFIG_SHELL) $(srctree)/usr/gen_initramfs.sh -o $@ $<
> +
> +modules-$(KERNELRELEASE)-$(ARCH).cpio: .tmp_modules_cpio
> +	$(Q)$(MAKE) $(build)=usr usr/gen_init_cpio
> +	$(call cmd,cpio)

Removing the '$(MAKE) $(build)=usr usr/gen_init_cpio' line and adding


PHONY += usr_gen_init_cpio
usr_gen_init_cpio: scripts_basic
	$(Q)$(MAKE) $(build)=usr usr/gen_init_cpio

modules-cpio-pkg: usr_gen_init_cpio


to top-level Makefile could be used to allow make to compile
gen_init_cpio in parallel instead of sequential.  And it simplifies a
possible move of gen_init_cpio from usr/ to scripts/, as Nathan
suggested.

What do you think?  (Top-level Makefile addition should probably better
be integrated into patch 1.)  I can also send this as a follow-up patch
after merging your patches.


Nevertheless,
Tested-by: Nicolas Schier <nsc@kernel.org>

If there are no further remarks, I am going to merge the patch set
before the weekend.

Thanks and kind regards,
Nicolas