image: add CONFIG_EXTRA_IMAGE_NAME

This allows an optional tag to be put in the .config file which is
included in the filename of the resulting images, so it's easier to
build images with different functionality for the same target hardware.

Signed-off-by: David Woodhouse <[email protected]>
Link: openwrt/openwrt#20984
Signed-off-by: Petr Štetiar <[email protected]>

Author: dwmw2

include/image.mk

@@ -41,6 +41,9 @@ KDIR=$(KERNEL_BUILD_DIR)
 KDIR_TMP=$(KDIR)/tmp
 DTS_DIR:=$(LINUX_DIR)/arch/$(LINUX_KARCH)/boot/dts
 
+ifeq ($(EXTRA_IMAGE_NAME),)
+EXTRA_IMAGE_NAME:=$(call qstrip,$(CONFIG_EXTRA_IMAGE_NAME))
+endif
 IMG_PREFIX_EXTRA:=$(if $(EXTRA_IMAGE_NAME),$(call sanitize,$(EXTRA_IMAGE_NAME))-)
 IMG_PREFIX_VERNUM:=$(if $(CONFIG_VERSION_FILENAMES),$(call sanitize,$(VERSION_NUMBER))-)
 IMG_PREFIX_VERCODE:=$(if $(CONFIG_VERSION_CODE_FILENAMES),$(call sanitize,$(VERSION_CODE))-)

package/base-files/image-config.in

@@ -5,6 +5,14 @@
 # See /LICENSE for more information.
 #
 
+config EXTRA_IMAGE_NAME
+	string
+	prompt "Extra image filename" if IMAGEOPT
+	default ""
+	help
+		Add this to the output image filenames, to distinguish between
+		different builds for the same hardware type.
+
 config TARGET_DEFAULT_LAN_IP_FROM_PREINIT
 	bool "Use preinit IP configuration as default LAN IP" if IMAGEOPT
 	default n