Extensible Firmware Interface is a specification that defines a software interface between an operating system and platform firmware

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How to fix broken EFI partition?

I have an iMac running OSX Lion. I also installed bootcamp and Windows 7. During the install of Windows 7 I wasn't paying complete attention and deleted and formatted the EFI partition. I didn't ...
3
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1answer
260 views

Does Windows, running on latest Apple computers, see boot disk partitioned as MBR or GPT?

From my understanding, the newest apple computers boot Windows in EFI mode. Traditionally, Windows has seen the boot disk as an MBR partitioned disk. In fact, the boot disk (i.e. /dev/disk0) has aways ...
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2answers
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Any solution to bootcamp windows 8.1 with macbook pro 15" 2010?

This question may at first glance seem to be a duplicate but I am asking for an update and clarification to an unsolved problem. After extensively scanning the web, it seems that the consensus is ...
7
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1answer
9k views

How to downgrade EFI firmware back to version 1.6

I'm trying to get a SATA III hard drive to work in my MacbookPro5,1. I think I've finally figured out that if I downgrade the EFI firmware to version 1.6, my computer will negotiate the link at SATA 1 ...
0
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1answer
95 views

EFI automounts on startup

After upgrading to the newest El Capitan from 10.10. to 10.11.1 - I guess - the normally invisible EFI partition appears on the desktop as a regular volume on different machines, if I choose to show ...
6
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2answers
9k views

Macbook Pro: How to disable discrete GPU permanently from EFI?

I'd like to disable the NVideo GTX 750M GPU on my Macbook Pro 15" (Retina, Mid 2014, OSX 10.10 Yosemite). I know I can use GfxCardStatus but I read I could have a more permanent solution by changing ...
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1answer
16k views

What does boot.efi actually do?

I understand that when a Mac's EFI system runs, it locates the file boot.efi in the /System/Library/CoreServices/ (blessed) directory and runs this as an EFI application (subverting a large part of ...
3
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1answer
164 views

Mysterious “EFI Boot” partition appearing at startup?

A few days ago, I tried installing Windows 8.1 on my late 2011 Mac by using disk utility to make a free space on my disk and a Windows 8.1 boot drive to install. While installing, my Mac recognized ...
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1answer
67 views

EFI Boot Windows 8.1 or 10 Install on MacPro4,1 / Mac Pro (Early 2009)

I would like to install Windows 8.1 or 10 on a separate single SSD disk in my MacPro4,1 (not yet flashed to MacPro5,1) using only EFI/GPT method. The machine has a 64Bit EFI (rEFIt reports version ...
2
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2answers
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How do I keep the Recovery HD and EFI partitions from automatically mounting on my MacBook Air?

I've set Finder preferences on my MacBook Air running OS X 10.9.1 to show everything on my desktop: I've noticed that storage partitions called Recovery HD and EFI appear there: What are they? ...
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4answers
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How to setup two OS X boot partitions plus Bootcamp and Data?

Is it possible to set up he following combination of partitions; how? two OS X partitions, each bootable (one for the main system, another for testing new OS X releases) a Bootcamp bootable ...
6
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2answers
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Why does Disk Utility create EFI partitions on external disks?

A technical told me about the EFI partition that... ...it's only there in case your computer will do an EFI update so the update files can be loaded onto the EFI partition. This is consistant with ...
2
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2answers
9k views

Unsupported hack or workaround to get 64-bit OS X to install on a MacBook Pro having only 32-bit EFI?

I want to install the 64-bit OS X 10.7 on my MacbookPro 2,1, which has a 64-bit processor, but only 32-bit EFI and Kernel Boot mode. I know that this is not officially supported, but I assume there ...
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2answers
1k views

Applying an old EFI update on a new version of OSX

I have El Capitan running on a MacMini 2010 that I use as a media player/server. The computer used to be my mother's and I have just noticed that she has never applied any of the firmware updates ...
1
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1answer
4k views

What does “EFI system partition couldn't be created” mean?

When trying to click "Repair Disk" on an external hard drive from Disk Utility, I got the following error message: ... Repairing the EFI system partition's file system Updating boot support ...
1
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1answer
769 views

Creating a EFI partition

I have been having trouble installing OS X Mavericks and I think I found the problem. It told me I couldn't boot up with Macintosh HD, so I verified my disk and I got this error: This disk doesn't ...
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3answers
12k views

“No Bootable Device” after failed Boot Camp installation (Windows 8 - 1TB Fusion Drive)

On my new iMac /w a 1TB Fusion Drive, I tried to install Windows 8 (still technically unsupported) using the following method: ...
0
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0answers
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firmwaresyncd - ESP Firmware.scap - /usr/standalone/i386/Firmware.scap

Please explain why /Volumes/EFI/EFI/APPLE/EXTENSIONS/Firmware.scap is overwritten every time you boot (as indicated below) though the file is not used while booting? host:~ user$ man 8 firmwaresyncd ...
0
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1answer
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/Volumes/EFI - Firmware.scap & MBA41_0077_B12_LOCKED.scap

Sorry for bad english - this is computer translation. See figure - MBA41_0077_B12_LOCKED.scap (# 2) - is the actual firmware of my MacBookAir4,1, which is was used to update firmware, but that such ...
0
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1answer
104 views

Resizing system partition

When I installed OSX Mavericks, I left free space after my system partition in case I wanted to install a second OS there. This has proved unnecessary — I've never modified the partition table — and ...