You may want to take a look at my diffs that add SA-1100 and SA-1110
support. I think they will be ready to check in soon, my assabet will
boot up to the point where it tries to mount the root device.

I couldn't find the Programmers Reference Manual on your website, so I
don't know how different the memory map on the IXP-1200 is from the
SA-1100.

All of the arm32 variants assume that the MMU is enabled before the
kernel is loaded.

On the SA-1110, the kernel is loaded at 0xc0000000, but this address has
already been remapped to 0xf0000000 by the bootloader.

The kernel then creates a new translation table which then also remaps
the peripheral devices above the end of kernel vm space.

What do you intend to use for a bootloader ?

Robert Swindells