Is there any means to use Cramfs and JFFS2 images as root disks?

[林建安 <Mickey@turtle.ee.ncku.edu.tw>]

Hello,
I had successfully booted up Linux with an NFS root.
Trying to boot up Linux with Cramfs and JFFS2 roots, I am wondering how to
pass parameters to Kernel.
I found that on some bootloaders, parameters are like these:
    rootfstype = jffs2 root=/dev/mtdblock3

But YAMON doesn't seem to support MTD BLOCK.
Therefore, how do I tell Kernel where the root image is on YAMON?

Thanks and regards,
Colin