[Transformer TF300T Android Development] JoinTheRealms:
I'm really struggling to remember, but if thats using the same init, it will most likely need a few more cmdline parameters to boot. Heres the init:

#!/bin/sh
#
# init script for linux
# Author - rabits
# Modified by moreD
#
# Initial script
#

export rootmnt=/root
export hostmnt=/host
export init=/sbin/init

panic() {
if command -v chvt >/dev/null 2>&1; then
chvt 1
fi

echo "$@"

/bin/sh -i </dev/console >/dev/console 2>&1
}

mountPartition() {
dev=$1
mp=$2
echo "Mounting fs..." 1>&2
return $(mount -t ext4 -o defaults,discard,errors=remount-ro,commit=60 "${dev}" "${mp}")
}

isMount() {
if mount | grep -q -- "$1"; then
return 0
fi

return 1
}

chown -R 0:0 /
chmod -R g-w /

# Mount basic system
if ! isMount "/dev"; then
[ -d /dev ] || mkdir -m 0755 /dev
if ! mount -t devtmpfs -o mode=0755 udev /dev; then
echo "W: devtmpfs not available, falling back to tmpfs for /dev"
mount -t tmpfs -o mode=0755 udev /dev
[ -e /dev/console ] || mknod -m 0600 /dev/console c 5 1
[ -e /dev/null ] || mknod /dev/null c 1 3
fi
mkdir /dev/pts
mount -t devpts -o noexec,nosuid,gid=5,mode=0620 devpts /dev/pts || true
fi
if ! isMount "/sys"; then
[ -d /sys ] || mkdir /sys
mount -t sysfs -o nodev,noexec,nosuid sysfs /sys
fi
if ! isMount "/proc"; then
[ -d /proc ] || mkdir /proc
mount -t proc -o nodev,noexec,nosuid proc /proc
fi
[ -d /tmp ] || mkdir /tmp
[ -d /root ] || mkdir -m 0700 /root

clear

# Set console powerdown 0
echo -ne "\033[14;0]" > /dev/console
# Set console blank 0
echo -ne "\033[9;0]" > /dev/console

# Disable dmesg to console
echo "1 1 1 7" > /proc/sys/kernel/printk

partition=$(cat /proc/cmdline | tr ' ' "\n" | grep 'partition')
[ $? -eq 0 ] || panic "No boot partition specified!"
partition=$(echo ${partition} | cut -d '=' -f2)

image=$(cat /proc/cmdline | tr ' ' "\n" | grep 'image' | cut -d '=' -f 2)
directory=$(cat /proc/cmdline | tr ' ' "\n" | grep 'directory' | cut -d '=' -f 2)

# boot using loop-mount
if [ -n "${image}" ]; then
[ -d ${hostmnt} ] || mkdir ${hostmnt}
echo "Mounting ${partition} on ${hostmnt}"
mountPartition ${partition} ${hostmnt}

echo "Loop-mounting ${hostmnt}${image} on ${rootmnt}"
mountPartition ${hostmnt}${image} ${rootmnt}

[ -d "${rootmnt}/mnt/host" ] || mkdir -p "${rootmnt}/mnt/host"
mount --bind ${hostmnt} "${rootmnt}/mnt/host"

# boot using rootbind
elif [ -n "${directory}" ]; then
[ -d ${hostmnt} ] || mkdir ${hostmnt}
echo "Mounting ${partition} on ${hostmnt}"
mountPartition ${partition} ${hostmnt}

mount --bind ${hostmnt}${directory} ${rootmnt}

# boot from physical partition
else
echo "Mounting partition..."
mountPartition ${partition} ${rootmnt}
fi

echo
echo "====== Starting Linux ======"
echo

[ -d /etc ] || mkdir -m 0755 /etc
[ -d /run ] || mkdir -m 0755 /run

mkdir -p /var/lock

ln -sf /proc/mounts /etc/mtab

mount -t tmpfs -o "nosuid,size=20%,mode=0755" tmpfs /run
mkdir /run/initramfs
ln -s /run/initramfs /dev/.initramfs

if [ -f "/etc/hostname" ]; then
/bin/hostname -b -F /etc/hostname 2>&1 1>/dev/null
fi

# Copy kernel modules & firmware to rootfs
kernel_modules=`find /lib/modules -type d -mindepth 1 -maxdepth 1`
if [ -z "${kernel_modules}" ]; then
panic "Could not find kernel modules!"
fi
[ -d "${rootmnt}${kernel_modules}" ] || mkdir -p "${rootmnt}${kernel_modules}"
rm -rf "${rootmnt}${kernel_modules}"
cp -af "${kernel_modules}" "${rootmnt}${kernel_modules}"
[ -d "${rootmnt}/lib/vendor" ] || mkdir -p "${rootmnt}/lib/vendor"
rm -rf "${rootmnt}/lib/vendor/firmware"
cp -af "/lib/vendor/firmware" "${rootmnt}/lib/vendor/firmware"

# Preserve information on old systems without /run on the rootfs
if [ -d ${rootmnt}/run ]; then
mount -n -o move /run ${rootmnt}/run
else
# The initramfs udev database must be migrated:
if [ -d /run/udev ] && [ ! -d /dev/.udev ]; then
mv /run/udev /dev/.udev
fi
# The initramfs debug info must be migrated:
if [ -d /run/initramfs ] && [ ! -d /dev/.initramfs ]; then
mv /run/initramfs /dev/.initramfs
fi
umount /run
fi

# Move virtual filesystems over to the real filesystem
mount --bind /dev ${rootmnt}/dev

mount -n -o move /sys ${rootmnt}/sys
mount -n -o move /proc ${rootmnt}/proc

# Chain to real filesystem
exec run-init ${rootmnt} ${init} "$@" <${rootmnt}/dev/console >${rootmnt}/dev/console 2>&1
panic "Could not execute run-init."

This is specifically for a guest kernel(Linux rootfs). Afaik with kexec kernels the only way of modifying kernel cmdline is with the kernel config pre-compile. I'll look a bit deeper.