YAFFS on SD

Hi. Could anybody please explain how could I write a YAFFS image (created
with the mkyaffs2image tool) to an SD card so the default Linux kernel can
recognize it as a YAFFS2 partition and boot from there? Thanks.

you cannot write directly yaffs2 to a SD card, and as it supposed to be
used by NAND devices (on board memory) you should rather format SD card by
standard FS like VFAT, EXT2, EXT3 etc.. Then grab .tar file with your
rootfs (normally generated by openembedded besides .yaffs2 file) and untar
it directly to the card.

there are plenty articles about it for mini2440

http://code.google.com/p/mini2440/wiki/QEmuSDCardImage