From: John Thomson <git@johnthomson.fastmail.com.au>
Date: Thu, 15 Oct 2020 09:06:41 +0000 (+1000)
Subject: build: image: add append-dtb-elf helper
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=9a168b51c3a60c95ccd349dd3010615ba6b0e033;p=openwrt%2Fstaging%2Fthess.git

build: image: add append-dtb-elf helper

The mips kernel vmlinux image supports adding an empty ELF section
for DTB to be later inserted into with MIPS_ELF_APPENDED_DTB.

This ELF + inserted DTB image can then be directly booted on some
devices.

Example usage:
image/subtarget.mk:
KERNEL_NAME := vmlinux.elf
KERNEL_INITRAMFS_NAME := vmlinux-initramfs.elf
KERNEL := kernel-bin | append-dtb-elf

On mt7621 memory size needed to be manually specified.

Signed-off-by: John Thomson <git@johnthomson.fastmail.com.au>
---

diff --git a/include/image-commands.mk b/include/image-commands.mk
index 740d627fc7..ea94059d20 100644
--- a/include/image-commands.mk
+++ b/include/image-commands.mk
@@ -142,6 +142,13 @@ define Build/append-dtb
 	cat $(KDIR)/image-$(firstword $(DEVICE_DTS)).dtb >> $@
 endef
 
+define Build/append-dtb-elf
+	$(TARGET_CROSS)objcopy \
+		--set-section-flags=.appended_dtb=alloc,contents \
+		--update-section \
+		.appended_dtb=$(KDIR)/image-$(firstword $(DEVICE_DTS)).dtb $@
+endef
+
 define Build/install-dtb
 	$(call locked, \
 		$(foreach dts,$(DEVICE_DTS), \