Load file as a chain-loader. Like any other file loaded by the
filesystem code, it can use the blocklist notation to grab the first
sector of the current partition with `+1'. If you specify the
option --force, then load file forcibly, whether it has a
correct signature or not. This is required when you want to load a
defective boot loader, such as SCO UnixWare 7.1 (see SCO UnixWare).