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After trying to install Linux (CentOs) and it crashed I can no longer boot W10. I can only choose OS X and its recovery after the alt option key.... The EFI partition is renamed to blank / NO NAME, as you can see in the diskutil list before installing Linux:

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *500.3 GB disk0

1: EFI EFI 209.7 MB disk0s1

And after the Linux install crashed:

diskutil list

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *500.3 GB disk0

1: EFI NO NAME 208.7 MB disk0s1

Somehow the Linux install renamed the EFI partition to NO Name or blank and what more......

Does anyone know how I can resolve this?

By the way I did follow the steps of

http://www.makeuseof.com/tag/install-linux-macbook-pro/ to install CentOs instead of Ubuntu.

Without success ......

1 Answer 1

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Chances are it's not the renaming of the EFI System Partition (ESP) that's the problem. (I note also that its size has changed slightly -- but again, I don't think that's the issue.) Chances are the installation attempt has wiped out a hybrid MBR upon which Windows was reliant for booting. If so, restoring the hybrid MBR should fix the problem. You can do that with my gdisk program or with gptsync (which comes with the old rEFIt, my rEFInd fork of it, and as a standalone program in some Linux distributions). Apple's Disk Utility can also create hybrid MBRs, but I don't know of a way to force it to create one without making other changes to the disk. (Normally it'll do the job when you create a FAT partition, for instance.)

Another possibility is the exact opposite, depending on the nature of the boot problem: It could be that the failed installation, or your attempt to recover from it, has created a hybrid MBR where one had not previously existed. This is a more likely explanation if you installed Windows 10 directly, rather than if you upgraded to Windows 10 from an earlier version.

Unfortunately, Apple's early reliance on hybrid MBRs and subsequent shift away from them has created an environment in which you need to be an expert to recover from problems like yours.


EDIT:

Please don't create multiple answers, or use answers to ask more questions. Instead, edit your question or post follow-up questions as comments to answers. This site sorts answers by votes, so using multiple answers to carry out a conversation quickly becomes very confusing because it becomes impossible to follow the sequence of questions and answers.

Based on your gdisk output, you've currently got a standard protective MBR, which means a pure-GPT disk (not a hybrid MBR). Thus, you've got conflicting indications -- the efibootmgr output indicates a probable EFI-mode Windows install (at some point); but if it's not booting with the current partition table, that might hint at a BIOS-mode Windows install (at some point). It's also possible it's always been EFI-mode, but something's trashed the Windows boot loader.

Given that your ESP is now a different size than it had been, my best guess at this point is that you (or the CentOS installer) inappropriately deleted and re-created the ESP, thus destroying the Windows boot loader. If so, then this question and answers may be your best bet for recovery.


EDIT 2:

You can always edit your question if you need to add extensive information.

Also, in all the back-and-forth, I forgot you were dealing with a Mac. It's possible that your ESP retains Windows boot files, but the Mac just isn't displaying them. If so, installing my rEFInd boot manager may restore your ability to boot both OSes. Before you do that, though, you should determine whether there are Windows boot files on your ESP. (I believe that's what you mean by "MBR partition." You have no MBR partitions, since your disk is GPT-only.) Mount it and look for a file called EFI/Microsoft/Boot/bootmgfw.efi. If it's present, that's your Windows boot loader, and rEFInd should enable you to launch it. If it's absent, then you'll need to follow a Windows recovery procedure to restore it. In fact, you might want to search the ESP for any files with names that end in .efi; those are EFI boot loaders (and possibly related files, like drivers).

Deleting your ESP will not help, and could make matters worse! At this point, it appears that either files are missing from the ESP or you're lacking the ability to launch files from the ESP. In either case, deleting the ESP will, at best, do no good. If there are relevant files on the ESP, deleting the ESP will just make matters worse.

2
  • Hi Rod, I understand it about the answer and comments only it is impossible to put tables in the comments, that it still will be readable.... About the CentOs destroy I agree with you that it did create a standard 500 MB MBR partition. I searched the Internet to find a solution for this issue and found fixedbyvonnie.com/2013/12/… If this will not help there is nothing left to do than I will erase the MBR partition. Do you agree?
    – BenKit
    Nov 10, 2015 at 18:02
  • Please see my second edit above.
    – Rod Smith
    Nov 10, 2015 at 18:54

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