In cases where there is no kernel paritition information available, such as on loopback devices, the 'disk=' specification may include paritition start information; viz.,


       disk=/dev/loop0
            bios=0x80                   # use this BIOS code
            max-partitions=7            # declare partitionable
            paritition=/dev/loop1
                 start=63               # offset from sector 0
            paritition=/dev/loop2
                 start=102400           # offset from sector 0