image: allow building FIT and uImage with ramdisk

Instead of embedding the initrd cpio archive into the kernel, allow
for having an external ramdisk added to the FIT or uImage.
This is useful to overcome kernel size limitations present in many
stock bootloaders, as the ramdisk is then loaded seperately and doesn't
add to the kernel size. Hence we can have larger ramdisks to host ie.
installers with all binaries to flash included (or a web-based
firmware selector).
In terms of performance and total size the differences are neglectible.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

1 files changed, 27 insertions, 1 deletions

diff --git a/scripts/mkits.sh b/scripts/mkits.sh
index 59ff3a2d15..ecaba8e965 100755
--- a/scripts/mkits.sh
+++ b/scripts/mkits.sh
@@ -24,6 +24,7 @@ usage() {
 	printf "\n\t-a ==> set load address to 'addr' (hex)"
 	printf "\n\t-e ==> set entry point to 'entry' (hex)"
 	printf "\n\t-f ==> set device tree compatible string"
+	printf "\n\t-i ==> include initrd Blob 'initrd'"
 	printf "\n\t-v ==> set kernel version to 'version'"
 	printf "\n\t-k ==> include kernel image 'kernel'"
 	printf "\n\t-D ==> human friendly Device Tree Blob 'name'"
@@ -37,10 +38,11 @@ usage() {
 
 FDTNUM=1
 ROOTFSNUM=1
+INITRDNUM=1
 HASH=sha1
 LOADABLES=
 
-while getopts ":A:a:c:C:D:d:e:f:k:n:o:v:r:S" OPTION
+while getopts ":A:a:c:C:D:d:e:f:i:k:n:o:v:r:S" OPTION
 do
 	case $OPTION in
 		A ) ARCH=$OPTARG;;
@@ -51,6 +53,7 @@ do
 		d ) DTB=$OPTARG;;
 		e ) ENTRY_ADDR=$OPTARG;;
 		f ) COMPATIBLE=$OPTARG;;
+		i ) INITRD=$OPTARG;;
 		k ) KERNEL=$OPTARG;;
 		n ) FDTNUM=$OPTARG;;
 		o ) OUTPUT=$OPTARG;;
@@ -96,6 +99,27 @@ if [ -n "${DTB}" ]; then
 	FDT_PROP="fdt = \"fdt@$FDTNUM\";"
 fi
 
+if [ -n "${INITRD}" ]; then
+	INITRD_NODE="
+		initrd@$INITRDNUM {
+			description = \"${ARCH_UPPER} OpenWrt ${DEVICE} initrd\";
+			${COMPATIBLE_PROP}
+			data = /incbin/(\"${INITRD}\");
+			type = \"ramdisk\";
+			arch = \"${ARCH}\";
+			os = \"linux\";
+			hash@1 {
+				algo = \"crc32\";
+			};
+			hash@2 {
+				algo = \"${HASH}\";
+			};
+		};
+"
+	INITRD_PROP="ramdisk=\"initrd@${INITRDNUM}\";"
+fi
+
+
 if [ -n "${ROOTFS}" ]; then
 	dd if="${ROOTFS}" of="${ROOTFS}.pagesync" bs=4096 conv=sync
 	ROOTFS_NODE="
@@ -141,6 +165,7 @@ DATA="/dts-v1/;
 				algo = \"$HASH\";
 			};
 		};
+${INITRD_NODE}
 ${FDT_NODE}
 ${ROOTFS_NODE}
 	};
@@ -153,6 +178,7 @@ ${ROOTFS_NODE}
 			${FDT_PROP}
 			${LOADABLES:+loadables = ${LOADABLES};}
 			${COMPATIBLE_PROP}
+			${INITRD_PROP}
 		};
 	};
 };"