kernel: mips: zboot: put appended dtb into a section

This will make a separated section for dtb appear in ELF, and we can
then use objcopy to patch a dtb into vmlinuz when RAW_APPENDED_DTB
is set in kernel config.

command to patch a dtb:
objcopy --set-section-flags=.appended_dtb=alloc,contents \
        --update-section=.appended_dtb=<target>.dtb vmlinuz vmlinuz-dtb

Signed-off-by: Chuanhong Guo <[email protected]>

target/linux/generic/pending-5.4/311-MIPS-zboot-put-appended-dtb-into-a-section.patch

@@ -0,0 +1,36 @@
+From 7d1531c81c0fb4c93bea8dc316043ad0e4d0c270 Mon Sep 17 00:00:00 2001
+From: Chuanhong Guo <[email protected]>
+Date: Sun, 25 Oct 2020 23:19:40 +0800
+Subject: [PATCH] MIPS: zboot: put appended dtb into a section
+
+This will make a separated section for dtb appear in ELF, and we can
+then use objcopy to patch a dtb into vmlinuz when RAW_APPENDED_DTB
+is set in kernel config.
+
+command to patch a dtb:
+objcopy --set-section-flags=.appended_dtb=alloc,contents \
+        --update-section=.appended_dtb=<target>.dtb vmlinuz vmlinuz-dtb
+
+Signed-off-by: Chuanhong Guo <[email protected]>
+---
+ arch/mips/boot/compressed/ld.script | 9 ++++++---
+ 1 file changed, 6 insertions(+), 3 deletions(-)
+
+--- a/arch/mips/boot/compressed/ld.script
++++ b/arch/mips/boot/compressed/ld.script
+@@ -31,9 +31,12 @@ SECTIONS
+ 		CONSTRUCTORS
+ 		. = ALIGN(16);
+ 	}
+-	__appended_dtb = .;
+-	/* leave space for appended DTB */
+-	. += 0x100000;
++
++	.appended_dtb : {
++		__appended_dtb = .;
++		/* leave space for appended DTB */
++		. += 0x100000;
++	}
+ 
+ 	_edata = .;
+ 	/* End of data section */