I've look around here and Apple's support community, but can't find my exact issue. I recently reinstalled Windows 10 to my MacBook Pro (Mid 2012), added a partition to start on installing Linux, and now OS X doesn't see the Windows 10 partition at all. I can still hold down alt/option to start it up, but I would like to have the option to have it automatically start to Windows 10, which I don't anymore.
sudo fdisk /dev/disk0 returned the following:
Disk: /dev/disk0 geometry: 29185/255/63 [468862128 sectors]
Signature: 0xAA55
Starting Ending
#: id cyl hd sec - cyl hd sec [ start - size]
------------------------------------------------------------------------
1: EE 0 0 2 - 25 127 14 [ 1 - 409639] <Unknown ID>
2: AF 25 127 15 - 1023 254 63 [ 409640 - 233553880] HFS+
*3: 07 1023 254 63 - 1023 254 63 [ 234225664 - 204800] HPFS/QNX/AUX
4: 07 1023 254 63 - 1023 254 63 [ 234430464 - 234428416] HPFS/QNX/AUX
sudo gdisk /dev/disk0 returned this:
Disk /dev/disk0: 468862128 sectors, 223.6 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): F33219B5-A986-430B-8674-23055706EF16
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 468862094
Partitions will be aligned on 8-sector boundaries
Total free space is 234693781 sectors (111.9 GiB)
Number Start (sector) End (sector) Size Code Name
1 40 409639 200.0 MiB EF00 EFI System Partition
2 409640 233963519 111.4 GiB AF00 Untitled
3 234225664 234430463 100.0 MiB 0700 BOOTCAMP
Of course, Disk Utility was SO helpful by showing this:
I don't want to reinstall Windows 10 AGAIN, and I can't seem to find any information that actually helps with this issue. Any assistance would be appreciated.
Best Answer
As you stated, you can hold down the option key at startup to invoke the Startup Manager. If you hold down the control key while selecting one of the displayed partitions, then chosen partition will become the new default startup partition.