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Questions tagged [efi]

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

43
votes
5answers
147k views

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

I'd like to disable the NVidia GTX 750M GPU on my MacBook Pro 15" (Retina, Mid 2014, Mac OS X 10.10 Yosemite). I know I can use GfxCardStatus but I read I could have a more permanent solution by ...
23
votes
5answers
147k views

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 ...
9
votes
1answer
17k views

How to fix broken GPT, GUID and unmountable, no type volumes?

I have a Macbook Pro with retina, Yosemite and 500GB hard drive. I tried to install Windows using Bootcamp and accidentally deleted a partition, now my Mac cannot boot anymore. This is the output from ...
3
votes
1answer
467 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 ...
3
votes
2answers
7k views

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 ...
2
votes
2answers
716 views

Accidently deleted some small sized partitions when installing Windows. OSX Partition wont boot

First off my problem is incredibly similar to this thread where the answer was almost reached but wasn't fully finished. Accidently deleted some small sized partitions when installing WIndows(Bootcamp)...
3
votes
1answer
24k 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 ...
2
votes
2answers
11k 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 1....
10
votes
1answer
15k 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 ...
2
votes
1answer
2k views

What is involved in converting a PC video card to have boot screen on the Mac?

I've got a PC video card that I'd like to get boot screen support for on my Mac Pro. In particular, it is a Gigabyte R9 270X. The card is supported on the Mac once it boots, but I would like to get ...
4
votes
1answer
25k 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
votes
3answers
3k views

Windows 10 EFI on MacPro 4,1 -> 5,1

I'm attempting an EFI install of Windows 10 on a 2009 (4,1) Mac Pro firmware upgraded to 5,1. I'm running High Sierra, and installing Windows 10 on a second partition on the same disk. I have no ...
2
votes
2answers
10k views

Where is the EFI stored on the macbook and is it possible to restore a previous EFI firmware version?

I recently upgraded my macbook pro 2008 (not unibody, running 10.6.8) to mountain lion. Directly after the upgrade finished the machine ran smoothly. But after a reboot it does not boot at all (no ...
4
votes
11answers
5k views

OSX Boot drive selection screen is slow, un-responsive and takes forever to load in Macbook Pro (early 2015)

I have a Macbook Pro Retina 13" (Early 2015) and I have a bootcamp partition with Windows 10 installed in it. Also, there is an Ubuntu Linux on another partition, so it’s a triple boot computer. I’m ...
1
vote
2answers
3k views

How to change the GPT partition type of an EFI partition?

I have a perplexing problem with the EFI partition on my boot SSD. The GPT partition type is "Microsoft Basic Data". On all other drives in my system, including my Carbon Copy Cloner clone of my boot ...
0
votes
1answer
3k views

/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 ...
2
votes
2answers
6k views

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? Is ...
4
votes
3answers
12k views

GRUB 2 error – “fb: switching to radeondrmfb from EFI VGA”

Whenever I try to boot Arch, Mint or Debian Linux from a USB stick using GRUB 2 on my Mac with compatibility mode, it freezes on this error (given in the question title). I've tried every available, ...
0
votes
4answers
8k views

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 partition ...
0
votes
1answer
601 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 ...
8
votes
2answers
7k views

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 ...
4
votes
2answers
14k 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 ...
3
votes
1answer
22k views

Disable wireless network card Mac OS X [duplicate]

I wonder if there is any way, how to turn off / disable the wireless network interface or driver, so I cannot connect to WiFi from running OS. I have MacBook Pro with OS X Mavericks. The reason for ...
2
votes
1answer
4k views

Is it possible to reinstall MacBook firmware?

iOS devices have DFU mode, which enable one to completely reinstall the firmware and operating system. Do MacBook devices have something similar? Is the firmware automatically reinstalled upon an OS ...
1
vote
1answer
1k 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 ...
1
vote
1answer
6k 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
vote
2answers
4k 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
vote
1answer
61 views

Testing EFI integrity under Linux

The utility in this article: High Sierra automatically checks EFI firmware each week looks like it will improve security on a Mac running macOS, but is it available for Linux too?
1
vote
1answer
376 views

How to resize Apple partition?

How to resize for Linux? /dev/disk0 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *250.1 GB disk0 1: ...
1
vote
3answers
13k 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: http://arstechnica.com/information-technology/2012/11/no-support-no-...
0
votes
1answer
3k views

Installing El Capitan from a bootable DVD

I have El Capitan on a bootable DVD. I restart my Mac and hold the option key until the disks come up and I choose EFI Boot (name of the disk is different than what it shows at the time of booting). ...
0
votes
1answer
232 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 ...
0
votes
1answer
536 views

How to restore motherboard firmware on an unresponsive MBP mid-2009?

My EFI was version 1.7 and I downgraded it to 1.6 by following the instructions in the answer given on How to downgrade EFI firmware back to version 1.6. (I made it to the end of step 4 and heard the "...