Previous versons of OS X and macOS automatically converted pure GPT drives to hybrid GPT/MBR format when the 2nd, 3rd, and/or 4th GPT partitions were formatted "MS DOS (FAT)" by the Disk Utility application or the diskutil
command. I am not sure when this changed, but this no longer happens under High Sierra (macOS 10.13.2).
My Mac needs the hybrid format in order to BIOS boot the installed Windows operating system.
What is a procedure to manually convert the drive back to the hybrid format?
Below is the output from the command diskutil list disk0
.
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.0 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_APFS Container disk1 249.5 GB disk0s2
3: Microsoft Basic Data BOOTCAMP 200.0 GB disk0s3
4: Microsoft Basic Data COMMON 50.0 GB disk0s4
5: Apple_HFS Refind 200.0 MB disk0s5
The BOOTCAMP volume is NTFS formatted and the COMMON volume is FAT32 formatted.
Note: The next two commands were executed after starting up from macOS Recovery.
Below is the output from the command gpt -r show /dev/disk0
.
start size index contents
0 1 PMBR
1 1 Pri GPT header
2 32 Pri GPT table
34 6
40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
409640 487304680 2 GPT part - 7C3457EF-0000-11AA-AA11-00306543ECAC
487714320 496
487714816 390623232 3 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
878338048 2048
878340096 97654784 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
975994880 696
975995576 390616 5 GPT part - 48465300-0000-11AA-AA11-00306543ECAC
976386192 176315
976562507 32 Sec GPT table
976562539 1 Sec GPT header
Below is the output from the command fdisk /dev/disk0
.
Disk: /dev/disk0 geometry: 60788/255/63 [976562540 sectors]
Signature: 0xAA55
Starting Ending
#: id cyl hd sec - cyl hd sec [ start - size]
------------------------------------------------------------------------
1: EE 1023 254 63 - 1023 254 63 [ 1 - 976562539] <Unknown ID>
2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused