initramfs: refactor the initramfs build rules

Currently, usr/gen_initramfs.sh takes care of all the use-cases:

 [1] generates a cpio file unless CONFIG_INITRAMFS_SOURCE points to
     a single cpio archive

 [2] If CONFIG_INITRAMFS_SOURCE is the path to a cpio archive,
     use it as-is.

 [3] Compress the cpio file according to CONFIG_INITRAMFS_COMPRESSION_*
     unless it is passed a compressed archive.

To simplify the script, move [2] and [3] to usr/Makefile.

If CONFIG_INITRAMFS_SOURCE is the path to a cpio archive, there is
no need to run this shell script.

For the cpio archive compression, you can re-use the rules from
scripts/Makefile.lib .

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

1 files changed, 60 insertions, 29 deletions

diff --git a/usr/Makefile b/usr/Makefile
index 4ca452197834..244862bfb765 100644
--- a/usr/Makefile
+++ b/usr/Makefile
@@ -3,55 +3,86 @@
 # kbuild file for usr/ - including initramfs image
 #
 
-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)"
+# cmd_bzip2, cmd_lzma, cmd_lzo, cmd_lz4 from scripts/Makefile.lib appends the
+# size at the end of the compressed file, which unfortunately does not work
+# with unpack_to_rootfs(). Make size_append no-op.
+override size_append := :
 
-# clean rules do not have CONFIG_INITRAMFS_COMPRESSION.  So clean up after all
-# possible compression formats.
-clean-files += initramfs_data.cpio*
+compress-$(CONFIG_INITRAMFS_COMPRESSION_NONE)	:= shipped
+compress-$(CONFIG_INITRAMFS_COMPRESSION_GZIP)	:= gzip
+compress-$(CONFIG_INITRAMFS_COMPRESSION_BZIP2)	:= bzip2
+compress-$(CONFIG_INITRAMFS_COMPRESSION_LZMA)	:= lzma
+compress-$(CONFIG_INITRAMFS_COMPRESSION_XZ)	:= xzmisc
+compress-$(CONFIG_INITRAMFS_COMPRESSION_LZO)	:= lzo
+compress-$(CONFIG_INITRAMFS_COMPRESSION_LZ4)	:= lz4
 
-# 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
+$(obj)/initramfs_data.o: $(obj)/initramfs_inc_data
 
-#####
-# Generate the initramfs cpio archive
+ramfs-input := $(strip $(shell echo $(CONFIG_INITRAMFS_SOURCE)))
+cpio-data :=
+
+# If CONFIG_INITRAMFS_SOURCE is empty, generate a small initramfs with the
+# default contents.
+ifeq ($(ramfs-input),)
+ramfs-input := $(srctree)/$(src)/default_cpio_list
+endif
+
+ifeq ($(words $(ramfs-input)),1)
+
+# If CONFIG_INITRAMFS_SOURCE specifies a single file, and it is suffixed with
+# .cpio, use it directly as an initramfs.
+ifneq ($(filter %.cpio,$(ramfs-input)),)
+cpio-data := $(ramfs-input)
+endif
+
+# If CONFIG_INITRAMFS_SOURCE specifies a single file, and it is suffixed with
+# .cpio.*, use it directly as an initramfs, and avoid double compression.
+ifeq ($(words $(subst .cpio.,$(space),$(ramfs-input))),2)
+cpio-data := $(ramfs-input)
+compress-y := shipped
+endif
+
+endif
+
+# For other cases, generate the initramfs cpio archive based on the contents
+# specified by CONFIG_INITRAMFS_SOURCE.
+ifeq ($(cpio-data),)
+
+cpio-data := $(obj)/initramfs_data.cpio
 
 hostprogs-y := gen_init_cpio
-ramfs-input := $(if $(filter-out "",$(CONFIG_INITRAMFS_SOURCE)), \
-			$(shell echo $(CONFIG_INITRAMFS_SOURCE)),$(srctree)/$(src)/default_cpio_list)
-ramfs-args  := \
-        $(if $(CONFIG_INITRAMFS_ROOT_UID), -u $(CONFIG_INITRAMFS_ROOT_UID)) \
-        $(if $(CONFIG_INITRAMFS_ROOT_GID), -g $(CONFIG_INITRAMFS_ROOT_GID))
 
-# $(datafile_d_y) is used to identify all files included
+# .initramfs_data.cpio.d is used to identify all files included
 # in initramfs and to detect if any files are added/removed.
 # Removed files are identified by directory timestamp being updated
 # The dependency list is generated by gen_initramfs.sh -l
-ifneq ($(wildcard $(obj)/$(datafile_d_y)),)
-	include $(obj)/$(datafile_d_y)
-endif
-
-quiet_cmd_initfs = GEN     $@
-      cmd_initfs = $(CONFIG_SHELL) $< -o $@ -l $(obj)/$(datafile_d_y) $(ramfs-args) $(ramfs-input)
-
-targets := $(datafile_y)
+-include $(obj)/.initramfs_data.cpio.d
 
 # do not try to update files included in initramfs
 $(deps_initramfs): ;
 
+quiet_cmd_initfs = GEN     $@
+      cmd_initfs = \
+	$(CONFIG_SHELL) $< -o $@ -l $(obj)/.initramfs_data.cpio.d \
+	$(if $(CONFIG_INITRAMFS_ROOT_UID), -u $(CONFIG_INITRAMFS_ROOT_UID)) \
+	$(if $(CONFIG_INITRAMFS_ROOT_GID), -g $(CONFIG_INITRAMFS_ROOT_GID)) \
+	$(ramfs-input)
+
 # We rebuild initramfs_data.cpio if:
 # 1) Any included file is newer than initramfs_data.cpio
 # 2) There are changes in which files are included (added or deleted)
 # 3) If gen_init_cpio are newer than initramfs_data.cpio
 # 4) Arguments to gen_initramfs.sh changes
-$(obj)/$(datafile_y): $(src)/gen_initramfs.sh $(obj)/gen_init_cpio $(deps_initramfs) FORCE
+$(obj)/initramfs_data.cpio: $(src)/gen_initramfs.sh $(obj)/gen_init_cpio $(deps_initramfs) FORCE
 	$(call if_changed,initfs)
 
+endif
+
+$(obj)/initramfs_inc_data: $(cpio-data) FORCE
+	$(call if_changed,$(compress-y))
+
+targets += initramfs_data.cpio initramfs_inc_data
+
 subdir-$(CONFIG_UAPI_HEADER_TEST) += include