[PATCH v2 0/2] kbuild: add target to build a cpio containing modules

[PATCH v2 0/2] kbuild: add target to build a cpio containing modules

[Ahmad Fatoum]

---
Changes in v2:
- Add Simon's Tested-by and Reviewed-by
- rename to modules-cpio-pkg (Nathan)
- add separator/doc comment heading (Thomas)
- Make temp directory ignoring and cleanup automatic (Thomas)
- Use CONFIG_SHELL instead of shebang (Thomas)
- Use -o instead of redirecting stdout when creating cpio (Thomas)
- Drop superfluous -f as $(build)= overrides it (Thomas)
- Add extra preparatory patch that makes hostprogs := gen_init_cpio
  unconditional
- Link to v1: https://lore.kernel.org/r/20251115-cpio-modules-pkg-v1-1-01d5a0748442@pengutronix.de

---
Ahmad Fatoum (1):
      initramfs: add gen_init_cpio to hostprogs unconditionally

Sascha Hauer (1):
      kbuild: add target to build a cpio containing modules

 scripts/Makefile.package | 20 ++++++++++++++++++++
 usr/Makefile             |  4 ++--
 2 files changed, 22 insertions(+), 2 deletions(-)
---
base-commit: e9a6fb0bcdd7609be6969112f3fbfcce3b1d4a7c
change-id: 20251115-cpio-modules-pkg-70d85a69892b

Best regards,
-- 
Ahmad Fatoum <a.fatoum@pengutronix.de>

[PATCH v2 1/2] initramfs: add gen_init_cpio to hostprogs unconditionally

[Ahmad Fatoum]

gen_init_cpio is currently only needed when an initramfs cpio archive is
to be created out of CONFIG_INITRAMFS_SOURCE's contents. In other cases,
it's not added to hostprogs and no make target is available.

In preparation to use the host program from Makefile.package, define it
unconditionally. The program will still only be built as needed.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 usr/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/usr/Makefile b/usr/Makefile
index f1779496bca78b4a56651b6af7221675ec7ade7a..e8f42478a0b76540180d191042cd58d3e4381f19 100644
--- a/usr/Makefile
+++ b/usr/Makefile
@@ -16,6 +16,8 @@ obj-$(CONFIG_BLK_DEV_INITRD) := initramfs_data.o
 
 $(obj)/initramfs_data.o: $(obj)/initramfs_inc_data
 
+hostprogs := gen_init_cpio
+
 ramfs-input := $(CONFIG_INITRAMFS_SOURCE)
 cpio-data :=
 
@@ -48,8 +50,6 @@ ifeq ($(cpio-data),)
 
 cpio-data := $(obj)/initramfs_data.cpio
 
-hostprogs := gen_init_cpio
-
 # .initramfs_data.cpio.d is used to identify all files included
 # in initramfs and to detect if any files are added/removed.
 # Removed files are identified by directory timestamp being updated

-- 
2.47.3

Re: [PATCH v2 1/2] initramfs: add gen_init_cpio to hostprogs unconditionally

[Simon Glass]

On Tue, 25 Nov 2025 at 06:18, Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:
>
> gen_init_cpio is currently only needed when an initramfs cpio archive is
> to be created out of CONFIG_INITRAMFS_SOURCE's contents. In other cases,
> it's not added to hostprogs and no make target is available.
>
> In preparation to use the host program from Makefile.package, define it
> unconditionally. The program will still only be built as needed.
>
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  usr/Makefile | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Simon Glass <sjg@chromium.org>

[PATCH v2 2/2] kbuild: add target to build a cpio containing modules

[Ahmad Fatoum]

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

Re: [PATCH v2 2/2] kbuild: add target to build a cpio containing modules

[Nicolas Schier]

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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

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Re: [PATCH v2 0/2] kbuild: add target to build a cpio containing modules

[Nathan Chancellor]

On Tue, Nov 25, 2025 at 02:18:18PM +0100, Ahmad Fatoum wrote:
> 
> ---
> Changes in v2:
> - Add Simon's Tested-by and Reviewed-by
> - rename to modules-cpio-pkg (Nathan)
> - add separator/doc comment heading (Thomas)
> - Make temp directory ignoring and cleanup automatic (Thomas)
> - Use CONFIG_SHELL instead of shebang (Thomas)
> - Use -o instead of redirecting stdout when creating cpio (Thomas)
> - Drop superfluous -f as $(build)= overrides it (Thomas)
> - Add extra preparatory patch that makes hostprogs := gen_init_cpio
>   unconditional
> - Link to v1: https://lore.kernel.org/r/20251115-cpio-modules-pkg-v1-1-01d5a0748442@pengutronix.de
> 
> ---
> Ahmad Fatoum (1):
>       initramfs: add gen_init_cpio to hostprogs unconditionally
> 
> Sascha Hauer (1):
>       kbuild: add target to build a cpio containing modules
> 
>  scripts/Makefile.package | 20 ++++++++++++++++++++
>  usr/Makefile             |  4 ++--
>  2 files changed, 22 insertions(+), 2 deletions(-)
> ---
> base-commit: e9a6fb0bcdd7609be6969112f3fbfcce3b1d4a7c
> change-id: 20251115-cpio-modules-pkg-70d85a69892b
> 
> Best regards,
> -- 
> Ahmad Fatoum <a.fatoum@pengutronix.de>
> 

Thanks a lot for implementing all of Thomas's suggestions (and thanks to
him for providing them). This series looks good to me and I can imagine
this being quite useful for testing.

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

Cheers,
Nathan

Re: [PATCH v2 0/2] kbuild: add target to build a cpio containing modules

[Thomas Weißschuh]

On Tue, Nov 25, 2025 at 02:18:18PM +0100, Ahmad Fatoum wrote:
> 
> ---
> Changes in v2:
> - Add Simon's Tested-by and Reviewed-by
> - rename to modules-cpio-pkg (Nathan)
> - add separator/doc comment heading (Thomas)
> - Make temp directory ignoring and cleanup automatic (Thomas)
> - Use CONFIG_SHELL instead of shebang (Thomas)
> - Use -o instead of redirecting stdout when creating cpio (Thomas)
> - Drop superfluous -f as $(build)= overrides it (Thomas)
> - Add extra preparatory patch that makes hostprogs := gen_init_cpio
>   unconditional
> - Link to v1: https://lore.kernel.org/r/20251115-cpio-modules-pkg-v1-1-01d5a0748442@pengutronix.de
> 
> ---
> Ahmad Fatoum (1):
>       initramfs: add gen_init_cpio to hostprogs unconditionally
> 
> Sascha Hauer (1):
>       kbuild: add target to build a cpio containing modules

For the series:

Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>

> 
>  scripts/Makefile.package | 20 ++++++++++++++++++++
>  usr/Makefile             |  4 ++--
>  2 files changed, 22 insertions(+), 2 deletions(-)
> ---
> base-commit: e9a6fb0bcdd7609be6969112f3fbfcce3b1d4a7c
> change-id: 20251115-cpio-modules-pkg-70d85a69892b
> 
> Best regards,
> -- 
> Ahmad Fatoum <a.fatoum@pengutronix.de>
> 

Re: [PATCH v2 0/2] kbuild: add target to build a cpio containing modules

[Nicolas Schier]

On Tue, 25 Nov 2025 14:18:18 +0100, Ahmad Fatoum wrote:
> 
> 

Applied, thanks!

[1/2] initramfs: add gen_init_cpio to hostprogs unconditionally
      https://git.kernel.org/kbuild/c/c83c9564
[2/2] kbuild: add target to build a cpio containing modules
      https://git.kernel.org/kbuild/c/2a9c8c0b

Best regards,
-- 
Nicolas