The attached patch adds a new option, CONFIG_XMODEM_ROM_STREAM, that allows LinuxBIOS to download its payload from the console via the XMODEM file transfer protocol.
This is handy if you want to try out a payload that's too big to fit into ROM, and you haven't yet gotten IDE or USB devices to work.
I chose to hook this into the ROM stream code so it can take advantage of the usual compression methods, but one could imagine moving it to a separate "serial stream" mechanism.
Comments are welcome.
--Ed