foreword
I have a Mac with both OS X and Windows, because both Windows and OS X can read and write exFAT partitions,
Therefore, if an exFAT partition is opened between Machintosh HD and Windows HD, it can be used as a shared file area.
I used Disk Utility to partition the Macintosh HD in OS X, opening an exFAT partition between the Machintosh HD and the Windows HD.
When I rebooted, I held down option and the boot options that came up after that didn't have Windows. This is because the disk is partitioned just now.
solve
Restart the MAC, press and hold COMMAND+R to enter recovery mode, open Terminal
csrutil disable #Turn off rootless
open terminal
sudo fdisk -e / dev / disk0
yanghaodeMacBook-Pro:~ yanghao$ sudo fdisk -e /dev/ disk0 Password: fdisk: could not open MBR file /usr/standalone/i386/boot0: No such file or directory Enter 'help' for information fdisk: 1> p Disk: /dev/disk0 geometry: 30515/255/63 [490234752 sectors] Offset: 0 Signature: 0xAA55 Starting Ending #: id cyl hd sec - cyl hd sec [ start - size] ------------------------------------------------------------------------ 1: EE 1023 254 63 - 1023 254 63 [ 1 - 409639] <Unknown ID> 2: AC 1023 254 63 - 1023 254 63 [ 409640 - 183869624] <Unknown ID> 3: AB 1023 254 63 - 1023 254 63[ 184279264 - 1269536 ] Darwin Boot * 4 : 07 1023 254 63 - 1023 254 63 [ 185548800 - 304685056 ] HPFS / QNX / AUX fdisk: 1>
Modify partition table
fdisk: 1> p Disk: /dev/disk0 geometry: 30515/255/63 [490234752 sectors] Offset: 0 Signature: 0xAA55 Starting Ending #: id cyl hd sec - cyl hd sec [ start - size] ------------------------------------------------------------------------ 1: EE 1023 254 63 - 1023 254 63 [ 1 - 409639] <Unknown ID> 2: AC 1023 254 63 - 1023 254 63 [ 409640 - 183869624] <Unknown ID> 3: AB 1023 254 63 - 1023 254 63 [ 184279264 - 1269536] Darwin Boot *4: 07 1023 254 63 - 1023 254 63 [ 185548800 - 304685056] HPFS/QNX/AUX fdisk: 1> setpid 4 Starting Ending #: id cyl hd sec - cyl hd sec [ start - size] ------------------------------------------------------------------------ * 4 : 07 1023 254 63 - 1023 254 63 [ 185548800 - 304685056 ] HPFS/QNX/ AUX Partition id ('0' to disable) [0 - FF]: [7] (? for help) 07 fdisk: 1> flag 4 Partition 4 marked active. fdisk:*1> p Disk: /dev/disk0 geometry: 30515/255/63 [490234752 sectors] Offset: 0 Signature: 0xAA55 Starting Ending #: id cyl hd sec - cyl hd sec [ start - size] ------------------------------------------------------------------------ 1: EE 1023 254 63 - 1023 254 63 [ 1 - 409639] <Unknown ID> 2: AC 1023 254 63 - 1023 254 63 [ 409640 - 183869624] <Unknown ID> 3: AB 1023 254 63 - 1023 254 63 [ 184279264 - 1269536] Darwin Boot *4: 07 1023 254 63 - 1023 254 63 [ 185548800 - 304685056] HPFS/QNX/AUX fdisk:*1> write Device could not be accessed exclusively. A reboot will be needed for changes to take effect.OK? [n] y Writing MBR at offset 0.
Restart the computer and press OPTION
