alternate usb_root specification?

I would like to pass an argument to the kernel which would cause it to look for its root filesystem based upon something other than the device name. This is because at each reboot, device names may change (e.g. what was once /dev/sda becomes /dev/sdb).

In the u-boot environment, I noticed that usb_root=/dev/sda1 is the default. I know how to change the environment variable with fw_setenv, but I've tried a couple different things (like "usb_root=LABEL=disklabel") to no avail. So, two questions:

1. What are the available kernel "root=" arguments (or point me to where I should look).
2. What syntax should be used for the env variable? I've tried things like:
usb_root='LABEL=disklable'
usb_root="LABEL=disklable"
with and without "\" in front of the quotes. Also, RTFM welcome here too :)

Thanks!
-Scott

Sounds like your looking for this Scan all USB devices and boot from the first bootable drive. :)

Thanks, I will give this a try.