Martin,

> # mount -v -t yaffs2ram yaffs2 /mnt/yaffs2ram
> mount: special device yaffs2 does not exist

you need something like /dev/mtdN or /dev/mtd/N for device. yaffs2 is not a
valid device name. Make sure you have properly created this device before you
use it.
N=0,1,2..

Sergei