MAC OS x disk repartitioning after Bootcamp Windows startup item is missing

Objective

I have a Mac with OS X and Windows two systems, both Windows and OS X can read and write exFAT partitions,

Therefore, if a EXFAT partition is opened between Machintosh HD and Windows HD, it can be used as a shared file area.

I partitioned Machintosh HD with disk Tools in OS X, and opened a EXFAT partition between Machintosh HD and Windows HD.

When the restart starts, I hold option, and then the startup options that appear do not have windows. This is due to the partition of the disk just now.

Solve

Restart your Mac, press and hold command+r to enter recovery mode, and open terminal

Csrutil Disable #关闭rootless

After modifying, restart your Mac, open the terminal

sudo fdisk-e/dev/disk0

yanghaodemacbook-pro:~ yanghao$sudoFDISK-E/dev/disk0Password:fdisk:could not open MBRfile/usr/standalone/i386/boot0:no suchfileor Directoryenter' Help'  forInformationfdisk:1>Pdisk:/dev/disk0 Geometry:30515/255/ the[490234752Sectors] Offset:0Signature:0xaa55starting ending #:IDCYL HD sec-cyl HD sec [Start-Size]------------------------------------------------------------------------1: EE1023 254   the-1023 254   the[1-409639] <unknown id>2: AC1023 254   the-1023 254   the[409640-183869624] <unknown id>3: AB1023 254   the-1023 254   the[184279264-1269536] Darwin Boot*4: - 1023 254   the-1023 254   the[185548800-304685056] Hpfs/qnx/Auxfdisk:1>

Modifying a partitioned table

fdisk:1> PDisk:/dev/disk0 Geometry:30515/255/ the[490234752Sectors] Offset:0Signature:0xaa55starting ending #:IDCYL HD sec-cyl HD sec [Start-Size]------------------------------------------------------------------------1: EE1023 254   the-1023 254   the[1-409639] <unknown id>2: AC1023 254   the-1023 254   the[409640-183869624] <unknown id>3: AB1023 254   the-1023 254   the[184279264-1269536] Darwin Boot*4: - 1023 254   the-1023 254   the[185548800-304685056] Hpfs/qnx/AUXfdisk: 1> setpid 4starting ending #:IDCYL HD sec-cyl HD sec [Start-Size]------------------------------------------------------------------------*4: - 1023 254   the-1023 254   the[185548800-304685056] Hpfs/qnx/auxpartitionID('0'To disable) [0-FF]: [7] (? forHelp -fdisk:1> Flag 4Partition4marked Active.fdisk:*1>Pdisk:/dev/disk0 Geometry:30515/255/ the[490234752Sectors] Offset:0Signature:0xaa55starting ending #:IDCYL HD sec-cyl HD sec [Start-Size]------------------------------------------------------------------------1: EE1023 254   the-1023 254   the[1-409639] <unknown id>2: AC1023 254   the-1023 254   the[409640-183869624] <unknown id>3: AB1023 254   the-1023 254   the[184279264-1269536] Darwin Boot*4: - 1023 254   the-1023 254   the[185548800-304685056] Hpfs/qnx/AUXfdisk: *1> WriteDevice could not being accessed exclusively. A reboot 'll be needed forChanges to take effect. OK?  [n] yWriting MBR at offset0.

Restart your computer by option

Bootcamp Windows Startup items after you repartition a MAC OS x disk