You can now set Biffboot configuration options via ethernet, using a very basic pyGTK application. Note that I'm still learning pyGTK, so some of the techniques used are going to look a little odd. Also, I'm rubbish at GUI design. Feel free to improve on this.
The source can be found at: https://bifferboard.svn.sourceforge.net/svnroot/bifferboard/slack/files/boot/bb_eth_setconfig.py.
IMPORTANT: bb_eth_setconfig.py allows disabling the network console via... THE NETWORK, and therefore allows you to deny yourself remote access to the bootloader. Be very careful about disabling the network console, especially if you don't have a serial console cable.
You need to run this as root, and root needs access to your X display (sorry).
The app starts off selecting the first interface it finds (change it to the network your Bifferboard is on), and waits for you to fill in a MAC.
When you enter a valid Bifferboard MAC the 'Connect' button will be activated and you can start looking for your Bifferboard by clicking on it. The 'Status' will change to 'Polling' and you should see the lights on your hub flickering frantically. At this point you should switch on the Bifferboard and a couple of seconds later the status should change to 'Connected'. Now the 'Write' button should be active, when you click it you will send the displayed configuration to the Bifferboard config block location.
Boot source, Serial console, Network console and boot image type cannot be messed up, but some options will result in disabling the 'Write' button if you input silly values.
Must start with 0x, and otherwise contain only hex characters (maximum 0xffffffff, which is clearly illegal with 32MB DRAM!).
Must start with 0x, and contain only hex chars. Must be a multiple of 65k (end in 0000), and must be at least 0x10000,
Changing the flash size should set the Kernel max value to the Biffboot default for the new size.