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Old 04-26-2012, 11:58 AM   #1
0624044
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Angry OS x prohibitory sign when booting (have triple boot (mac - ubuntu -windows))

Hi guys

I have a problem with booting my mac, when i boot os x i get the apple logo zith the loading cicle under it, but after a minute or so the apple logo changes in the prohibitory sign.

I had tripple boot (mac - ubuntu -windows) using rEFIt as boatloader. Then i had to reinstall windows (because of some bluescreen) and zhen i installed windows i accidentally deleted the EFI partition.

After i installed windows, os x still booted normally, but ubuntu didn't anymore (because i deleted the EFI partition?). So i googled my problem and i some guy on the internet said i had to rebuild my MBR table wit;

Code:
 fdisk -u /dev/disk0
I did and the next time i booted os x i got the prohibitory sign problem. I tried booting in Single user mode, but then i got the message:

still waiting for root device
still waiting for root device
...

i tried resetting my firmware by holding down the powerbutton for 30seconds or wo.
i tried resetting my PRAM and NVRAM zith cmd + option + p + r,
but all that didn't change.

when i hold down the option key at boot, i get the choice of REFIT and windows, but bot the Macintosh HD. Is there some way to delete refit from my mac and make it boot from the macintosh HD directly again? I tried changing the boot flag with a bootCD, but all that didn't work.

Or is there some way to restore the EFI partition as it was (or as it should be). I looked at my GPT table en MBR zith the ubuntu live CD and they look correct.

Another big big problem i have is that i dont have my os x install dvd anymore so i can't use that. do any of you know what exact the problem is why os x doesn't boot anymore?

Some help would be much appreciated, cause im losing my mind over here!!

thx anyway,
Tom
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Old 04-28-2012, 06:33 AM   #2
asmundkur
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The man page I have says for fdisk,
The DOS fdisk program can be used to divide space on the disk into parti-
tions and set one active. This fdisk program serves a similar purpose to
the DOS program. When called with no special flags, it prints the MBR
partition table of the specified device

So, while bearing in mind that I'm a complete novice as far as the command line interface is concerned, it looks to me that you've de-activated your Mac OS partition and your solution lies in re-activating it as the default - which means you should have its name disk1, disk2, disk3?
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Old 04-30-2012, 11:32 AM   #3
0624044
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Hi thx for the reply,

i have only one hard drive: disk0
and tree patitions, the first one is the OS X partition so disk1.

now how do i re-activate it as default? preferably in linux.

Code:
fdisk -e /dev/rdisk0
witch becomes in linux

Code:
fdisk -e /dev/sda1
but what is the equivalent of the -e argument for fdisk in linux?
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Old 04-30-2012, 12:02 PM   #4
asmundkur
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Sorry, but I'll be going out of my depth here if I try to help out. You'll need to study the man page for fdisk thoroughly, find the designation of your Mac OS X partition, and re-activate it as the default on your own unless someone else can guide you (hopefully not as casually as they apparently did to start your troubles!). Alternatively, seek Apple's expert help (which will, no doubt, cost you money).
Another quote from the man page for fdisk, which I hope helps:
The DOS fdisk program can be used to divide space on the disk into parti-
tions and set one active. This fdisk program serves a similar purpose to
the DOS program. When called with no special flags, it prints the MBR
partition table of the specified device, i.e.,

# fdisk fd0
Disk: fd0 geometry: 80/2/18 [2880 sectors]
Offset: 0 Signature: 0xAA55
Starting Ending
#: id cyl hd sec - cyl hd sec [ start - size]
----------------------------------------------------------------------
*1: A6 0 0 1 - 79 1 18 [ 0 - 2880] OpenBSD
2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused
3: A7 0 0 2 - 79 1 18 [ 1 - 2879] NEXTSTEP
4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

The geometry displayed is a synthetic geometry unless another geometry
has been selected using the -c, -h, -s, -S, and -b options. In the
future, fdisk will read the BIOS geometry from the IOKit registry.

In this example, the disk is divided into two partitions that happen to
fill the disk. The first partition overlaps the third partition. (Used
for debugging purposes.)

Edited to add man page detail.

Last edited by asmundkur; 04-30-2012 at 12:10 PM.
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Old 05-17-2012, 12:13 PM   #5
0624044
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Hey guys, sorry for the late reply but i solved my problem!
For those of you having a similar problem, here is how i solved mine:

I tried solving it with fdisk by
-creating a new MBR,
-removing the MBR so it would take the GPT to detect my partitions
- etc..

But all that did not work, if anything it made things worse! So if you don't fully understand fdisk and are absolutely certain what you're about to do, i strongly recommand you not to use it!

that aside here is how i solved my problem:

- I ended up using someone else's install DVD.
- booted from the DVD and selected my Macintosh HD as boot partition with the Disk Startup app and rebooted my mac
-The next time i booted, my macbook booted the OS X partition directly (so no rEFIt), but i still got the prohibitory sign
-I rebooted my macbook, but this time in SAFE MODE (By holding the shift button when you boot) not single user mode ( holding commans + s at boot)
-now my OS X booted in safe mode!!! hurray!!!
-In system preferences i selected my macintosh HD as startup disk (not sure if you have to do this, but i did it to be certain)
-rebooted my mac
-My OS X booted as normal again!!

Hope it can help saving someone else some time and anger
@asmundkur: thx for the help!
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