MbrSourcetype t = private {bootstrap_code : string;original_physical_drive : int;seconds : int;minutes : int;hours : int;disk_signature : int32;partitions : Partition.t list;}make ?disk_signature partitions constructs an MBR given a desired list of primary partitions. An Error _ is returned if:
The optional argument disk_signature specifies the disk signature to be written in the MBR. If disk_signature is not provided, the default value of 0l is used.
sizeof is the size of a master boot record in bytes (512 bytes)
default sector offset for first partition