kbuild: add target to build a cpio containing modules

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>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nicolas Schier <nsc@kernel.org>
Link: https://patch.msgid.link/20251125-cpio-modules-pkg-v2-2-aa8277d89682@pengutronix.de
Signed-off-by: Nicolas Schier <nsc@kernel.org>

diff --git a/scripts/Makefile.package b/scripts/Makefile.package
index 74bcb9e7f7a4516473481468a0fcf700c3bead33..83bfcf7cb09fd2d69b97e0c19a2b99c728835e8d 100644 (file)
--- 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'