grub: gptsync
16.3.30 gptsync
---------------
-- Command: gptsync device [partition[+/-[type]]] ...
Disks using the GUID Partition Table (GPT) also have a legacy
Master Boot Record (MBR) partition table for compatibility with the
BIOS and with older operating systems. The legacy MBR can only
represent a limited subset of GPT partition entries.
This command populates the legacy MBR with the specified PARTITION
entries on DEVICE. Up to three partitions may be used.
TYPE is an MBR partition type code; prefix with '0x' if you want to
enter this in hexadecimal. The separator between PARTITION and
TYPE may be '+' to make the partition active, or '-' to make it
inactive; only one partition may be active. If both the separator
and type are omitted, then the partition will be inactive.