MRKisThatKid Posted June 11, 2006 Share Posted June 11, 2006 As with others, in order to install the official public beta 2 of Vista I deleted the 200MB partition, which I believe is the EFI Partition. I'm going to reinstall XP, but also I want to recreate the EFI partition so that 1. boot camp assistant once again works and just in case any new firmware updates are released. I haven't managed to get anywhere with the GPT command. Tried it from a normal OSX Boot, from single-user mode and from the OSX Install dvd and it always tells me disk0 is busy. Even from the install dvd after umounting the main volume. Has anyone been successful doing this? Link to comment Share on other sites More sharing options...
nevermind1331 Posted June 11, 2006 Share Posted June 11, 2006 im pretty sure you cant without reformatting the drive. when you delete the efi partition, you also delete some gpt headers that cannot be easily replaced. back it up to an external hard drive and reinstall. Link to comment Share on other sites More sharing options...
JackSlater Posted June 11, 2006 Share Posted June 11, 2006 maybe this one will help, I'm not sure, though... http://docs.info.apple.com/article.html?artnum=303609 Link to comment Share on other sites More sharing options...
VanillaIcee Posted June 14, 2006 Share Posted June 14, 2006 Here's how. Not sure if it fully gives back your EFI partition, but it's good enough for Boot Camp and I think firmware updates will be able to use it. 1. In Vista, open up Computer Management and format the 200MB empty drive that was once your EFI partition as FAT32 (You can also do this with the Vista Disc, in case your Vista install is corrupted). 2. Reboot off of the Mac OS X Disc 3. Switch to Console 4. Type in "diskutil list" and note which partition is your Macintosh HD. In my case it was /dev/disk0. 5. Type in "fdisk -e <partition>". However it is important to note that you will need to insert an 'r' before the disk device name. For example, in my case I typed "fdisk -e /dev/rdisk0". 6. Type "print". This should list the partitions of your Macintosh HD. You should see a FAT32 200MB partition, followed by an HFS+ partition and the partition you used for Vista. If this does not match up, stop here and retry fdisk with another disk or give up. Note the start and size of the partition and write them down. 7. CAUTION (fdisk is very dangerous): type "edit <#>" where number is the number of the 200MB partition used for the EFI. In my case I typed "edit 1". 8. CAUTION: You will be prompted for a System identifier (id) for that partition. Type in EE, which is not in the list provided by the help. Once again, I am retyping the last line to ensure there are no typos. Type in EE, which is not in the list provided by the help. Choose the default [n] for the next question about editing. Enter in the identical start and stop numbers you recorded in the previous step. In my case the start was 2048, although I don't recall the end. 9. CAUTION: You are done, but the changes have not been written. If you might have made a mistake, cancel now and exit and nothing will be lost. I would type "print" and ensure that the starts and stops match the previous print done before the edit. If you as sure you entered everything correctly, type "write" and fdisk will write the new partition table. Please do not proceed with this step if you are not sure about the procedure. 10. Reboot into hard drive Mac OS X. 11. Use Boot Camp to remove Windows partition. I have done this TWICE and it works, but be very careful. Good luck. Link to comment Share on other sites More sharing options...
LasVegas Posted June 26, 2006 Share Posted June 26, 2006 I've found a better procedure than the above. Follow step one the same. Since almost all of us are using the actual boot disk of the Mac (disk0) I will write accordingly. After performing step one: 2. Boot the Mac OS X partition and hold Command-S to get into Single User mode. 3. Type "fdisk /dev/rdisk0" and look at the current partition map. Verify that the Mac partition (2) starts at 409640. If it doesn't, don't continue with these instructions! 4. Only if step 3 was correct, enter "fdisk -e /dev/rdisk0" 5. Type "edit 1" 6. Answer "EE" to the prompt for System ID, "n" when prompted about editing in CMS mode, "1" for the Start block and 409639 for the length (One less that step 3's start block). 7. Type "print" to verify your entries. It should read for partition 1: 1:EE 0 0 2- 25 127 14[ 1- 409639]<unknown ID> 8. If step 7 is correct, type "write" and reboot. If not, type "exit" and try again. This will restore the full 200MB EFI partition and Mac OS X will boot normally and allow you to update Firmware or BootCamp (when available). Vista will not boot until the partition is again erased with the Vista boot CD. DON'T TRY ERASING IT IN MAC OSX! I tried to and had to restore yet again! Link to comment Share on other sites More sharing options...
mediaman Posted June 27, 2006 Share Posted June 27, 2006 I am having some trouble with the above instructions? In step 6 is Partition Offset the same as Start Block, and is Partition Size the same as Length? When I print the results (before righting) the entry for my partition 1 is 1: EE 0 0 2 - 1023 254 63 [ 1- 409639]<unknown ID> instead of the one above? The entry for the FAT32 Partition (at the start) is 1:0B 0 32 33 - 25 126 37 [2048 407552] and the HFS+ Mac partition (2) does start at 409640 Link to comment Share on other sites More sharing options...
LasVegas Posted June 27, 2006 Share Posted June 27, 2006 The process is overwriting the FAT32 partition and assigning the entire space before partiton 2 to the EFI partition. Yes, the Start Block should be "1" and the Partition Size should be 409639. The smaller Size in partition 1 currently is because Windows left the first 2048 blocks unassigned. Link to comment Share on other sites More sharing options...
mediaman Posted June 28, 2006 Share Posted June 28, 2006 The process is overwriting the FAT32 partition and assigning the entire space before partiton 2 to the EFI partition. Yes, the Start Block should be "1" and the Partition Size should be 409639. The smaller Size in partition 1 currently is because Windows left the first 2048 blocks unassigned. How do I stop it doing this, then? As my 'Print' doesn't match your example Yours 1:EE 0 0 2- 25 127 14[ 1- 409639]<unknown ID> Mine 1: EE 0 0 2 - 1023 254 63 [ 1- 409639]<unknown ID> Worryingly though the 1023 254 63 section matches the HFS+ partition below it in the partition map? Link to comment Share on other sites More sharing options...
LasVegas Posted June 28, 2006 Share Posted June 28, 2006 No worry. That simply indicates you have a different drive than I have. As long as Partition 1's length is one less that partition 2's Start block it will work fine. Link to comment Share on other sites More sharing options...
mediaman Posted June 29, 2006 Share Posted June 29, 2006 No worry. That simply indicates you have a different drive than I have. As long as Partition 1's length is one less that partition 2's Start block it will work fine. Here is my before and after partition maps Original map 1 : 0B 0 32 33 - 25 126 37 [ 20448 - 407552] Win95 FAT-32 2 : AF 25 127 15 - 1023 254 63 [ 489648 - 436207616] HFS+ *3: 07 1023 254 63 - 1023 254 63 [436079400 - 53355312] HPFS/QNX/AUX 4 : 00 0 0 0 - 0 0 0 [ 0 - 0] unused Modified map 1 : EE 0 0 2 - 1023 254 63 [ 1 - 409639] <Unknown ID> 2 : AF 25 127 15 - 1023 254 63 [ 489648 - 436207616] HFS+ *3: 07 1023 254 63 - 1023 254 63 [436079400 - 53355312] HPFS/QNX/AUX 4 : 00 0 0 0 - 0 0 0 [ 0 - 0] unused This is what bothers me (expecially as I don't have a back up drive yet, never realised the larger ones where that expensive?). how come the first three partitions all have the same end points? Link to comment Share on other sites More sharing options...
Mack Posted July 25, 2006 Share Posted July 25, 2006 Just a word of thanks to you guys. I also grew bored with Vista and wanted my EFI back. This method worked without a hitch. Link to comment Share on other sites More sharing options...
mac86 Posted July 27, 2006 Share Posted July 27, 2006 Ok, I followed the instructions above and I cant launch Boot Camp. It keeps giving me the "you must update system software to launch..." error. I checked my partition info in single user mode and they match the above specs. I then updated the firmware to 1.0.1, I rebooted and zapped the pram and then once in os x tried to launch Boot Camp...no go. I then tried uninstalling and reinstalling Boot Camp and still no dice. Whenever I double click on the updaters for either SMC or iMac firmware updater each say that my system is up to date. Any ideas here? Link to comment Share on other sites More sharing options...
iDerf2006 Posted July 28, 2006 Share Posted July 28, 2006 Thanks LasVegas, this procedure worked perfectly for me! Link to comment Share on other sites More sharing options...
avioli Posted October 19, 2008 Share Posted October 19, 2008 Hey guys... I'm not using Boot Camp, but i'm on a hackintosh. Sorry if this is the wrong place to ask, but it is the only one related to EFI partition restoration. Here's what bothers me: I have used hacked OS X for long time and soon after 10.5.2 came out I have installed Leopard on fresh drive using GUID. The hacked version of the OS (Kaylway) alters the EFI (at least i think it does) so I want to revert it to the original (I want to install boot-132, which uses the original installation dvd, not hacked). Because the drive is divided in two - OS & Data partitions I don't want to reformat it, and I want to simply restore the EFI to the original. I have followed the solution above but "fdisk print" gives me this: Disk: /dev/rdisk0 geometry: 60801/255/63 [976773168 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: AF 1023 254 63 - 1023 254 63 [ 409640 - 209453056] HFS+ 3: AF 1023 254 63 - 1023 254 63 [ 210124840 - 766386144] HFS+ 4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused Why these starting and ending cylinders, heads and sectors are the same?!?!? Is it wrong or normal? Can I continue? I really don't want to screw partition #3 Link to comment Share on other sites More sharing options...
champcohort Posted November 15, 2008 Share Posted November 15, 2008 Can u help me? I got this one and I feel something may wrong. when I did step 4: After type "fdisk -e /dev/rdisk0" I received this: "fdisk: Could not open MBR file /usr/standalone/i386/boot0: No such file or directory" And can I ask this one, also? What is the MBR file? Link to comment Share on other sites More sharing options...
Recommended Posts