How to build a ramdisk image for use as a root filesystem with AR531X

Overview:
In order to boot from a ramdisk root file system image, you will
first create a root directory structure in the "rootdir" directory.
Then run "make" to create a compressed root file system image in
ramdisk.gz.  Finally, copy this image into your kernel source tree
and remake the kernel.  The ramdisk image is then built into the
kernel.  When the kernel starts, it is uncompressed into RAM, and
used as a root file system.

If you'd like to use a pre-built ramdisk.gz rather than build
one yourself:
  cp arch/mips/ar531x/RAMDISK/ramdisk.gz arch/mips/ramdisk/ramdisk.gz

Here are the detailed steps to build your own:

1) Modify Makefile to point KERNEL_SOURCE at your linux source tree.

2) Copy whatever additional files/directories/links you'd like to
   under rootdir.  Note that you're limited to CONFIG_BLK_DEV_RAM_SIZE
   1KB blocks, as specified in your linux/.config file.
   Examples:
	Copy busybox to rootdir/bin/
        [NOTE: Copy busybox.links to this directory to
        cause the makelinks script to automatically
        set up all of the necessary busybox command links
        in the rootdir/bin directory].

	Copy any wireless driver modules into rootdir tree

   You might want to make a copy of the rootdir directory
   before you modify it, just in case you want to get back
   to the original.

3) LOGIN AS ROOT (e.g. "su") and type "make"

4) Copy the resulting ramdisk.gz to your linux source tree under
       arch/mips/ramdisk/ramdisk.gz
   (or "make install" will do this step for you)
