This is FreeBIOS. At this point it's really linuxbios, FreeBIOS is mostly gone. 

To see how to build a target, you should look into the HOWTO directory. 

We should, but do not, have a HOWTO for each target. Sorry, Ron's fault.
But the SIS 630 is a good place to start. 

To make this you need a newer GAS. Our version that works is

GNU assembler version 2.9.5 (i386-redhat-linux) using BFD version
2.9.5.0.22

This comes with redhat 6.2  or later. Almost everybody has this now.

