fs/cpio: allow users to provide their own dracut modules

Dracut modules can only be looked for in HOST_DIR/lib/dracut/modules.d/
as dracut does not offer the possibility to look elsewhere.

Installing files in HOST_DIR/ can do done either from a host-package, or
via a post-built script; there is no overlay like there is for target/.
This is a bit cumbersome.

Additional modules are most probably developped in a relatively tight
loop with the configuration files, so it makes sense to expose both
close together.

Add an option to the fs/cpio filesystem, so users can point to a list
of modules to install.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Cc: Thierry Bultel <thierry.bultel@linatsea.fr>
Cc: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

fs/cpio/Config.in

@@ -29,6 +29,11 @@ endchoice
 
 if BR2_TARGET_ROOTFS_CPIO_DRACUT
 
+config BR2_TARGET_ROOTFS_CPIO_DRACUT_MODULES
+	string "extra dracut modules"
+	help
+	  Space-separated list of directories containing dracut modules.
+
 config BR2_TARGET_ROOTFS_CPIO_DRACUT_CONF_FILES
 	string "dracut configuration files"
 	default "fs/cpio/dracut.conf"

fs/cpio/cpio.mk

@@ -50,6 +50,13 @@ else ifeq ($(BR2_TARGET_ROOTFS_CPIO_DRACUT),y)
 
 ROOTFS_CPIO_DEPENDENCIES += host-dracut
 
+ROOTFS_CPIO_DRACUT_MODULES = $(call qstrip,$(BR2_TARGET_ROOTFS_CPIO_DRACUT_MODULES))
+ifeq ($(BR_BUILDING),y)
+ifneq ($(words $(ROOTFS_CPIO_DRACUT_MODULES)),$(words $(sort $(notdir $(ROOTFS_CPIO_DRACUT_MODULES)))))
+$(error No two dracut modules can have the same basename, check your BR2_TARGET_ROOTFS_CPIO_DRACUT_MODULES setting)
+endif
+endif
+
 ROOTFS_CPIO_DRACUT_CONF_FILES = $(call qstrip,$(BR2_TARGET_ROOTFS_CPIO_DRACUT_CONF_FILES))
 ifeq ($(BR_BUILDING),y)
 ifeq ($(ROOTFS_CPIO_DRACUT_CONF_FILES),)
@@ -68,11 +75,14 @@ ROOTFS_CPIO_OPTS += --no-kernel
 endif
 
 define ROOTFS_CPIO_CMD
-	mkdir -p $(ROOTFS_CPIO_DIR)/tmp $(ROOTFS_CPIO_DIR)/confdir
+	mkdir -p $(ROOTFS_CPIO_DIR)/tmp $(ROOTFS_CPIO_DIR)/confdir $(HOST_DIR)/lib/dracut/modules.d
 	touch $(ROOTFS_CPIO_DIR)/empty-config
 	$(foreach cfg,$(ROOTFS_CPIO_DRACUT_CONF_FILES), \
 		cp $(cfg) $(ROOTFS_CPIO_DIR)/confdir/$(notdir $(cfg))
 	)
+	$(foreach m,$(ROOTFS_CPIO_DRACUT_MODULES), \
+		cp -a $(m)/* $(HOST_DIR)/lib/dracut/modules.d/
+	)
 	$(HOST_DIR)/bin/dracut \
 		$(ROOTFS_CPIO_OPTS) \
 		-c $(ROOTFS_CPIO_DIR)/empty-config \