Simple (sample) shell script to perform kexec hardboot for Xperia M/M Dual.

do_kexec.sh

#!/boot/busybox sh

set -x

echo "About to kexec new kernel..."

if [ -x "/cache/kexec" ] && [ -f "/cache/stock_kernel" ] && [ -f "/cache/ramdisk" ]; then
	# Builds the new cmdline

	# The portion starting from "androidboot.emmc=true" is added by
	# the bootloader, therefore we extract it and append it to the
	# cmdline for the new kernel
	CUR_CMDLINE=`/boot/busybox sed 's/^.*\( androidboot.emmc.*\)/\1/' /proc/cmdline`
	# warmboot=0x77665501 stands for normal reboot
	# Don't let warmboot=0x77665502 (recovery) slip through
	CUR_CMDLINE=`echo "$CUR_CMDLINE" | /boot/busybox sed 's/\(warmboot=0x\)[0-9a-fA-F]*/\177665501/'`

	if [ "$CUR_CMDLINE" = "" ]; then
		echo "Extracted cmdline is empty. Is this Xperia M/M Dual?"
	else
		NEW_CMDLINE="panic=3 console=ttyHSL0,115200,n8 androidboot.hardware=qcom user_debug=31 msm_rtb.filter=0x3F ehci-hcd.park=3$CUR_CMDLINE"
		echo "Newformed cmdline is:"
		echo "$NEW_CMDLINE"
		/boot/busybox sync
		/boot/busybox mount -o remount,ro /system
		/boot/busybox mount -o remount,ro /data
		/boot/busybox mount -o remount,ro /cache
		/boot/busybox sync
		/cache/kexec --load-hardboot /cache/stock_kernel --initrd=/cache/ramdisk --mem-min=0x85000000 --mem-max=0x87ffffff --command-line="$NEW_CMDLINE"
		/boot/busybox sync
		/cache/kexec -e
		echo "It appears that kexec has failed..."
	fi
else
	echo "kexec, kernel or ramdisk missing!"
fi