Q: Boot Camp won't start after OSX Yosemite upgrade
Like so many others, I installed OSX Yosemite this morning and now Boot Camp no longer works.
After I updated to Yosemite I restarted my computer, held down alt, and was presented nothing but a Macintosh HD. I followed “Loner T’s” instructions…
ndiskutil list
diskutil cs list
sudo gpt -vv -r show /dev/disk0
sudo fdisk /dev/disk0
Enter you password when prompted.
…and now a windows option is available during startup. However, when selected, all I get is a black screen with "A disk read error occurred" notice.
I’m in serious trouble if I cannot repair this issue. PLEASE HELP.
iMac, OS X Yosemite (10.10), Windows 7
Posted on Oct 18, 2014 12:00 PM
1. The goal of the next steps is to move the GPT#4 entry from
1752625152 200898560 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
to
1118887936 834635769
2. Download GPT Fdisk from http://sourceforge.net/projects/gptfdisk/.
3. Run the following commands. Use "?" if you need to see the built-in help.
sudo gdisk /dev/disk0
p
d
4
n
4
(Put the correct Start value here)
(Put the correct End value here)
p
w
y
Now run sudo gpt -vv -r show /dev/disk0 and verify. Reboot.
4. Run the command sudo dd if=/dev/rdisk0s4 count=1 2>/dev/null | hexdump -C and verify that you can see "R.NTFS".
5. In Gdisk, re-create a Hybrid MBR with 2 3 4 (and allow it to add the EFI into the MBR). There is a space between 2 and 3 and 4.
sudo gdisk /dev/disk0
type 'r' for Recovery Transformation Menu
type 'h' for Hybrid MBR
Recovery/transformation command (? for help): h
WARNING! Hybrid MBRs are flaky and dangerous! If you decide not to use one,
just hit the Enter key at the below prompt and your MBR partition table will
be untouched.
Type from one to three GPT partition numbers, separated by spaces, to be
added to the hybrid MBR, in sequence: 2 3 4
Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): y
Creating entry for GPT partition #2 (MBR partition #2)
Enter an MBR hex code (default AF):
Set the bootable flag? (Y/N): n
Creating entry for GPT partition #3 (MBR partition #3)
Enter an MBR hex code (default AB):
Set the bootable flag? (Y/N): n
Creating entry for GPT partition #4 (MBR partition #4)
Enter an MBR hex code (default 07):
Set the bootable flag? (Y/N): y
type 'w' to write MBR
type 'y' to confirm the write.
6. Reboot into OS X.
7. Verify that Bootcamp volume is visible in Finder.
8. Verify that you can see files in Bootcamp volume in Finder.
9. Verify that you can select Bootcamp in System Preferences -> Startup Disk.
10. Select Bootcamp and reboot. If you need startup repair, use your Windows installation media.
Posted on Oct 19, 2014 11:27 AM
