fs: new intermediate rootfs-common to gather common dependencies

Before we can create an intermediate tarball for all filesystems, we
nedd to move the common dependencies needed to generate that
intermediate tarball, rather than leave those dependencies to each
filesystem.

So, we introduce rootfs-common, which gathers all those common
dependencies.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

fs/common.mk

@@ -34,6 +34,24 @@ ROOTFS_DEVICE_TABLES = $(call qstrip,$(BR2_ROOTFS_DEVICE_TABLE) \
 USERS_TABLE = $(FS_DIR)/users_table.txt
 ROOTFS_USERS_TABLES = $(call qstrip,$(BR2_ROOTFS_USERS_TABLES))
 
+ROOTFS_COMMON_TAR = $(FS_DIR)/rootfs.common.tar
+
+.PHONY: rootfs-common
+rootfs-common: $(ROOTFS_COMMON_TAR)
+
+ROOTFS_COMMON_DEPENDENCIES = \
+	host-fakeroot host-makedevs \
+	$(if $(PACKAGES_USERS)$(ROOTFS_USERS_TABLES),host-mkpasswd)
+
+.PHONY: $(ROOTFS_COMMON_TAR)
+# When doing the common tarball, we're not really doing a rootfs.
+$(ROOTFS_COMMON_TAR): ROOTFS=
+$(ROOTFS_COMMON_TAR): $(ROOTFS_COMMON_DEPENDENCIES) target-finalize
+	@:
+
+rootfs-common-show-depends:
+	@echo $(ROOTFS_COMMON_DEPENDENCIES)
+
 # Since this function will be called from within an $(eval ...)
 # all variable references except the arguments must be $$-quoted.
 define inner-rootfs
@@ -41,9 +59,7 @@ define inner-rootfs
 ROOTFS_$(2)_DIR = $$(FS_DIR)/$(1)
 ROOTFS_$(2)_TARGET_DIR = $$(BASE_TARGET_DIR)
 
-# extra deps
-ROOTFS_$(2)_DEPENDENCIES += host-fakeroot host-makedevs \
-	$$(if $$(PACKAGES_USERS)$$(ROOTFS_USERS_TABLES),host-mkpasswd)
+ROOTFS_$(2)_DEPENDENCIES += rootfs-common
 
 ifeq ($$(BR2_TARGET_ROOTFS_$(2)_GZIP),y)
 ROOTFS_$(2)_COMPRESS_EXT = .gz
@@ -76,7 +92,6 @@ endif
 
 $$(BINARIES_DIR)/rootfs.$(1): ROOTFS=$(2)
 $$(BINARIES_DIR)/rootfs.$(1): FAKEROOT_SCRIPT=$$(ROOTFS_$(2)_DIR)/fakeroot
-$$(BINARIES_DIR)/rootfs.$(1): target-finalize
 $$(BINARIES_DIR)/rootfs.$(1): $$(ROOTFS_$(2)_DEPENDENCIES)
 	@$$(call MESSAGE,"Generating root filesystem image rootfs.$(1)")
 	rm -rf $(FS_DIR) $$(ROOTFS_$(2)_DIR)