I made a multi-file imgage as described here http://www.denx.de/twiki/bin/view/DULG/CombiningKernelAndRamdisk but I can't boot it bacuse the kernel does not find the ramdisk image. How to say to the kernel where to find it? Isuspect I'm missing some command line parameters ...
Have you successfully booted with two single-file images?
I have found (after much agony) that booting the 2.6 kernel from U-Boot requires modification of the kernel code in order for it to be able to read an initrd image from flash (there is an old patch floating around for the 2.4 kernel somewhere). Personally i decided against this, and experimented with copying the rom image into ram.
Copying from rom to ram will work, as long as the image file is a raw gzip file (not created with mkimage), as the kernel doesn't seem to understand anything else. If there is a command to manually uncompress an image file into ram i am not aware of it.
Hope this helps,
-Patrick