• I think its(this page) needed to clarify the intent, preferred style and function of the image/Makefile.
• I believe one of the following should be placed here:
  • Adding a new platform (new buildroot howto section?)
  • OpenWrt Buildroot - new platform (new page/how-to on adding platform support to the buildroot system)

Inside your platform directory you will need to create a file to tell the buildroot system how to process the results of a compiled kernel. Most of the work is done automatically by image.mk but different platforms and individual devices will need specific work for images to be useful.

See example.

Can be used to append data to image but often used simply to move to another directory such as $(KDIR)

Example:

cat $(LINUX_DIR)/arch/arm/boot/zImage >> $(KDIR)/$(call zimage_name,$(1))

This section allows automated modification of the elf file before loading onto the device. The file can be found with this line

$(BIN_DIR)/$(IMG_PREFIX)-vmlinux.elf

Appears to be used to call the other build defines (squashfs, jffs2-64k, jffs2-128k, etc) after they were processed and their resulting files were placed into $(TARGET_DIR)

to call a define for each use:

$(call Image/Build/$(1),$(1))

Example of: trunk/target/linux/platform/image/Makefile

# 
# Copyright (C) 2010 OpenWrt.org
#
# This is free software, licensed under the GNU General Public License v2.
# See /LICENSE for more information.
#
include $(TOPDIR)/rules.mk
include $(INCLUDE_DIR)/image.mk
 
define Image/Prepare
 
endef
 
define Image/Build/Initramfs
	$(BIN_DIR)/$(IMG_PREFIX)-vmlinux.elf
endef
 
define Image/BuildKernel
 
endef
 
define Image/Build/jffs2-64k
	dd if=$(KDIR)/root.$(1) of=$(BIN_DIR)/openwrt-$(BOARD)-$(1).img bs=65536 conv=sync
endef
 
define Image/Build/jffs2-128k
	dd if=$(KDIR)/root.$(1) of=$(BIN_DIR)/openwrt-$(BOARD)-$(1).img bs=131072 conv=sync
endef
 
define Image/Build/squashfs
	$(call prepare_generic_squashfs,$(KDIR)/root.squashfs)
endef
 
define Image/Build
	$(call Image/Build/$(1),$(1))
endef

have a look at your copy of trunk/include/image.mk

Kernel options required by the platform + kernel version.

CONFIG_QCOM_PM=y
CONFIG_QCOM_QFPROM=y
CONFIG_QCOM_RPMCC=y

Kernel specific device source. Primarily the location of device DTS files. You will need to add a new device dts here and reference in image/Makefile under DEVICE_DTS.

Kernel source additions. No changes for basic device additions.

Platform wide device definition and common package set. Generally does not require modification when adding additional platform devices.

include $(TOPDIR)/rules.mk
 
ARCH:=arm
BOARD:=ipq806x
BOARDNAME:=Qualcomm Atheros IPQ806X
FEATURES:=squashfs nand fpu ramdisk
CPU_TYPE:=cortex-a15
CPU_SUBTYPE:=neon-vfpv4
MAINTAINER:=John Crispin <john@phrozen.org>
 
KERNEL_PATCHVER:=4.14
 
KERNELNAME:=zImage Image dtbs
 
include $(INCLUDE_DIR)/target.mk
DEFAULT_PACKAGES += \
	kmod-leds-gpio kmod-gpio-button-hotplug swconfig \
	kmod-ata-core kmod-ata-ahci kmod-ata-ahci-platform \
	kmod-usb-core kmod-usb-ohci kmod-usb2 kmod-usb-ledtrig-usbport \
	kmod-usb3 kmod-usb-dwc3-of-simple kmod-usb-phy-qcom-dwc3 \
	kmod-ath10k-ct wpad-basic \
	uboot-envtools
 
$(eval $(call BuildTarget))

Device specific image creation parameters and image generation functions.

define Device/zyxel_nbg6817
	DEVICE_DTS := qcom-ipq8065-nbg6817
	KERNEL_SIZE := 4096k
	BLOCKSIZE := 64k
	BOARD_NAME := nbg6817
	RAS_BOARD := NBG6817
	RAS_ROOTFS_SIZE := 20934k
	RAS_VERSION := "V1.99(OWRT.9999)C0"
	SUPPORTED_DEVICES += nbg6817
	DEVICE_VENDOR := ZyXEL
	DEVICE_MODEL := NBG6817
	DEVICE_PACKAGES := ath10k-firmware-qca9984-ct e2fsprogs kmod-fs-ext4 losetup
	$(call Device/ZyXELImage)
endef
TARGET_DEVICES += zyxel_nbg6817

Initialization scripts. Instantiation of LED, wifi and upgrade/install routines. etc. Many changes needed to add new device.

Board core firmware.