1 files changed, 61 insertions, 0 deletions
diff --git a/usr/Makefile b/usr/Makefile
new file mode 100644
index 000000000..138c18cef
--- /dev/null
+++ b/usr/Makefile
@@ -0,0 +1,61 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# kbuild file for usr/ - including initramfs image
+#
+
+klibcdirs:;
+PHONY += klibcdirs
+
+suffix_y = $(subst $\",,$(CONFIG_INITRAMFS_COMPRESSION))
+datafile_y = initramfs_data.cpio$(suffix_y)
+datafile_d_y = .$(datafile_y).d
+AFLAGS_initramfs_data.o += -DINITRAMFS_IMAGE="usr/$(datafile_y)"
+
+# clean rules do not have CONFIG_INITRAMFS_COMPRESSION.  So clean up after all
+# possible compression formats.
+clean-files += initramfs_data.cpio*
+
+# Generate builtin.o based on initramfs_data.o
+obj-$(CONFIG_BLK_DEV_INITRD) := initramfs_data.o
+
+# initramfs_data.o contains the compressed initramfs_data.cpio image.
+# The image is included using .incbin, a dependency which is not
+# tracked automatically.
+$(obj)/initramfs_data.o: $(obj)/$(datafile_y) FORCE
+
+#####
+# Generate the initramfs cpio archive
+
+hostprogs-y := gen_init_cpio
+initramfs   := $(CONFIG_SHELL) $(srctree)/$(src)/gen_initramfs_list.sh
+ramfs-input := $(if $(filter-out "",$(CONFIG_INITRAMFS_SOURCE)), \
+			$(shell echo $(CONFIG_INITRAMFS_SOURCE)),-d)
+ramfs-args  := \
+        $(if $(CONFIG_INITRAMFS_ROOT_UID), -u $(CONFIG_INITRAMFS_ROOT_UID)) \
+        $(if $(CONFIG_INITRAMFS_ROOT_GID), -g $(CONFIG_INITRAMFS_ROOT_GID))
+
+# $(datafile_d_y) is used to identify all files included
+# in initramfs and to detect if any files are added/removed.
+# Removed files are identified by directory timestamp being updated
+# The dependency list is generated by gen_initramfs.sh -l
+ifneq ($(wildcard $(obj)/$(datafile_d_y)),)
+	include $(obj)/$(datafile_d_y)
+endif
+
+quiet_cmd_initfs = GEN     $@
+      cmd_initfs = $(initramfs) -o $@ $(ramfs-args) $(ramfs-input)
+
+targets := $(datafile_y)
+
+# do not try to update files included in initramfs
+$(deps_initramfs): ;
+
+$(deps_initramfs): klibcdirs
+# We rebuild initramfs_data.cpio if:
+# 1) Any included file is newer then initramfs_data.cpio
+# 2) There are changes in which files are included (added or deleted)
+# 3) If gen_init_cpio are newer than initramfs_data.cpio
+# 4) arguments to gen_initramfs.sh changes
+$(obj)/$(datafile_y): $(obj)/gen_init_cpio $(deps_initramfs) klibcdirs
+	$(Q)$(initramfs) -l $(ramfs-input) > $(obj)/$(datafile_d_y)
+	$(call if_changed,initfs)