The LinuxBIOS project started from a paper presented at Usenix 2000 titled "LOBOS: Linux Os Boots OS." (PDF attached here.)
Their basic idea is to have a Linux kernel that automatically, at boot time, reads in a new kernel from some other source and then boots it, without even launching userspace.
What we would like is to have a tiny userspace that allows incoming telnet connections and provides a basic shell that allows the kernel and root filesystem locations and types to be specified, and then loads the kernel and starts it up. (I believe that is what the Netwinder Nettrom does.) That's exactly what the kexec system call does; so the question is: is kexec supported on MIPS? And will the userspace kexec tools work on the WL-700gE?
While we have not answered these questions, it seems that kexec-tools may have MIPS support merged into baseline. It is not totally clear to us whether kexec will be supported on brcm4780. And if kernel configuration provides such an option, that doesn't necessarily mean it will really work ....
Our understanding is that kexec is the system call. kexec-tools provides the userspace tool that sets things up so that the system call can be used, and then invokes it. We need to learn a lot more about this stuff. In the meantime, we will skip the entire Linux bootloader scheme, and just burn the real runtime kernel into flash so that CFE can boot it directly.