GPT and MBR partition tables synchronisation tool

 gptsync is a utility to maintain an MBR partition table synchronised with
 a GPT partition table used as reference. The resulting MBR partition table
 can contain up to 4 partitions; extended partitions are not supported.
 .
 An MBR partition table is required to use legacy bootloaders (lilo, grub) on
 EFI-based (Extensible Firmware Interface) machines like the Intel-based Macs.
 gptsync is usually used in combination with the rEFIt boot menu on such
 machines.