> The patched 2.6.19.2 kernel can not read it, gives errors

My 550-... patch is not fully compatible with the old yaffs1 layout,
because of the block status encoding. If mikrotik's 2.6 is using the old
layout, this is the expected behavior.

> I am suspecting that the RouterBoard tftp flash uses a differnet nand format
> compared to the RootBoot loader format. A tcpdump may or may not reveal some of
> the magic involved on this ...

I'm not sure about what you mean here, but this has nothing to do with
networking stuff AFAIK.

Andrea