IPFire 2.27 - Core Update 159 - Raspberry pi 4?

Hello,
maybe that’s a helpful hint.

https://forums.raspberrypi.com/viewtopic.php?t=319125
https://archlinuxarm.org/forum/viewtopic.php?f=67&t=15422

According to this threads i have modified the files boot.cmd and boot.scr and ipfire boots up until setup with a revision 1.4 board.

- booti ${kernel_addr_r} ${ramdisk_addr} ${fdt_addr_r};
+ booti ${kernel_addr_r} ${ramdisk_addr} ${fdt_addr};
- booti ${kernel_addr_r} - ${fdt_addr_r};
+ booti ${kernel_addr_r} - ${fdt_addr};

But after that it doesn’t go any further.
The keyboard does not work or the system hangs.

Regards
Michael