openwrt/target/linux/brcm2708/image/gen_rpi_sdcard_img.sh

#!/usr/bin/env bash

set -x 
[ $# -eq 5 ] || {
    echo "SYNTAX: $0 <file> <bootfs image> <rootfs image> <bootfs size> <rootfs size>"
    exit 1
}

OUTPUT="$1"
BOOTFS="$2"
ROOTFS="$3"
BOOTFSSIZE="$4"
ROOTFSSIZE="$5"

head=4
sect=63

set $(ptgen -o $OUTPUT -h $head -s $sect -l 4096 -t c -p ${BOOTFSSIZE}M -t 83 -p ${ROOTFSSIZE}M)

BOOTOFFSET="$(($1 / 512))"
BOOTSIZE="$(($2 / 512))"
ROOTFSOFFSET="$(($3 / 512))"
ROOTFSSIZE="$(($4 / 512))"

dd bs=512 if="$BOOTFS" of="$OUTPUT" seek="$BOOTOFFSET" conv=notrunc
dd bs=512 if="$ROOTFS" of="$OUTPUT" seek="$ROOTFSOFFSET" conv=notrunc