Running seL4 on a Pi4 b

Hi,

I’ve been trying to lean more about seL4. I have been trying to get the sel4test-driver image to run on a Raspberry pi 4 b and following along the How to
but this fails to load the kernel.
If i do an ls I can see the image is there, and then on doing a fatload I get a message

U-Boot> fatload mmc 0 0x10000000 sel4test-driver-image-arm-bcm2711
** Reading file would overwrite reserved memory **
Failed to load 'sel4test-driver-image-arm-bcm2711'

These are the contents of the SD card

U-Boot> fatls mmc 0
            overlays/
    47600   bcm2711-rpi-4-b.dtb
    52460   bootcode.bin
       51   config.txt
  2241664   start4.elf
            .Trash-214000077/
  5169084   sel4test-driver-image-arm-bcm2711
   602488   u-boot.bin

6 file(s), 2 dir(s)

This is the config.txt

arm_64bit=1
kernel=u-boot.bin
dtoverlay=disable-bt

If I had to guess, then probably there is some problem in the uboot. I’ve created the uboot following exactly how the How to guide explains,

git clone
git revert
make
make

I’m sure I’ve missed something here…
Has anyone done this, any ideas what I could be doing wrong…

Regards,
Amol