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

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Create EFI partition on external HDD for rEFInd

How can I install Ubuntu and Windows onto my external HDD which already has OS X installed on it? I want to install it using rEFInd boot manager. If I can create an EFI partition for my drive then I ...
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Why does my external HDD have an EFI partition?

When I ran diskutil list on my Mac, it showed an EFI partition plus my normal partition on my external disk. Why is it there? If I edit my EFI partition and it gets corrupt, will a format change it ...
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2answers
109 views

How can I install the newest EFI firmware upgrade from El Capitan?

I've got an early 2011 MacBook Pro (8,1) and I am trying to install the newest EFI firmware upgrade, however it only supports 10.8.5 and 10.9.5. Unfortunately I have no clue as to what the best ...
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1answer
877 views

Set EFI to boot Windows via (U)EFI one time

On my late 2012 Mac Mini, I have installed both Mac OS X Mavericks (with FileVault) and Windows 8.1 (natively, not via Bootcamp): /dev/disk0 #: TYPE NAME ...
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1answer
823 views

My CPU is running slow after a system restore (4x0.8 GHz). Turbo Boost is definitely not working. And how can I fix it?

Last weekend, my Macbok Air suffered a heart attack and I ended up doing several hard shutdowns due to an unresponsive system. In the end I had to do a full system restoration. Everything is working ...
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2answers
358 views

Getting my MacBook Air (2011) into Windows faster

Is there a way to reduce the time spent in EFI? It seems more than 15 seconds that the Mac (Macbook air 2011) stays with the screen grey before beginning to boot (or resume from hibernate) to ...
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3answers
1k views

Can't boot on OS X partition after resizing Windows partition

I initially had three bootable partitions: OS X Recovery for OS X Bootcamp (Windows 8) Now, on Windows, I decided to make my Windows partition smaller, reducing its size using the native Disk ...
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1answer
7k 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
137 views

GRUB 2 - “fb: swiutching to radeondrmfb from EFI VGA”

Whenever I try to boot Arch, Mint or Debian 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, up to ...
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1answer
160 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 ...
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44 views

Issue with OS X Startup Disk in System Preferences when using EFI dual boot

I have Windows booting EFI on my Mac mini (Late 2012). It has two physical drives with one EFI partition (on the OS X disk). If I option boot I see OS X and EFI (Windows) choices and everything works ...
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1k views

Hide “disk password” login option at EFI (Filevault) login screen

I encrypted my volume before installation and have added my user as FileVault user afterwards. Now I can login with either the disk password or my user login password at the EFI (Filevault) login ...
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2answers
266 views

How can the average user easily validate the integrity of their Mac's firmware?

How can the average user easily validate the integrity of their Mac's firmware? Before you downvote this question or lecture me on how I am paranoid and no one should ever need to do that, please ...
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1answer
69 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 ...
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1answer
10k views

How to transform an Apple Mac Mini intro a reliable Ubuntu Server?

This question is about what steps are needed for transforming an Apple Mac Mini into an Ubuntu server. Here are some areas: installing Ubuntu and making it to be bootable from EFI by default ...
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2answers
3k 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? ...
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14 views

15" MacBook Pro (2011) i7, 16GB ram, 1TB hybrid drive. EFI problem [duplicate]

Have been running in Win7 for awhile and needed to boot into Mac El Capitan. Option had my normal icons but my Mac partition now is labeled EFI Boot. Other icons are my Windows partition and Recovery ...
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1answer
457 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 ...
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0answers
171 views

Mac Pro, Boot into OSX without EFI after Bootcamp

I have a Mac Pro, early 2008. I installed Windows 10 using bootcamp. The mac came with an 8800gt, but I had a GTX680 from my other PC which I put in the mac, it is not the mac version so I don't get ...
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270 views

What is /Volumes/firmwaresyncd?

I keep seeing this in my logs: > 10/5/15 3:45:16.532 AM deleted[366]: normalizeUserMountpoint:738 > volRoot failed for /Volumes/firmwaresyncd.G3PNKw What is it? Is it related to the firmware ...
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237 views

How to use Testdisk under OS X recovery mode?

I accidentally broke the GUID, I suppose, when I was trying to solve the incorrect EFI partition problem. What I have now is: Disk1 is a 4 GB thumb drive with a recovery partition (disk1s2) I ...
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1answer
283 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 ...
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1answer
100 views

Boot from external USB3

I've recently bought an usb3 flash drive where I've put a live kali linux distribution. When I try to boot my early 2015 mac book pro (with Yosemite) from this usb3 drive I have two options: windows ...
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4answers
3k 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 ...
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139 views

HFS+ external drive missing EFI, will not mount on Mac

First off: Fear not, I have everything from this drive backed up. I'm just trying to reformat it, but I had someone else attempt it on Windows which doesn't look like it helped. I'm a novice but ...
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4answers
104k 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 ...
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310 views

Efibootmgr command for OS X

I have successfully been able to install Linux Mint on my Mac. The only issue is I cannot select the boot partition holding option. To fix it I booted into linux and ran sudo efibootmgr -o 1,80. This ...
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2answers
4k 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 ...
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2answers
342 views

How can I repair EFI?

The computer is a MacBook Air. I have OSX Yosemite and Linux Ubuntu 14.04 dual boot. I messed up and damaged my Mac EFI and hence OSX ceased to work. Recovery disk was destoyed too. FileVault is on ...
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1answer
95 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 ...
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2answers
600 views

Unable to use gpt to restore efi partition

I accidentally deleted my efi partition, which I now know is bad news bears. I found a guide here to restore it without losing data, but even though I'm booting from usb and have unmounted all ...
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133 views

Corrupt EFI Partition or Error b/c of Encryption? & Ghost Partition

I have a 2012 Mac Mini Server with two internal SSDs. Until recently, I had Mt. Lion installed on one of the SSDs, as my only boot drive, and used the other, rarely, for file storage. I created a ...
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1answer
413 views

How can I get Windows to install in Legacy (BIOS) boot on my mid-2012 MBP

I've got a 13" mid-2012 MBP running OS X 10.10.3 Yosemite. I've recently repaved it with a fresh install and now I'm getting round to Bootcamp`ing it. I've installed Windows 8.1 in EFI boot mode and ...
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3answers
116 views

Is my UEFI bugged?

I just received the new MacBook Pro 15" (with basic configuration). When I press 'Alt.' during the booting process, I don't see the recovery partition. Also, the interface is not gray as it used to ...
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2answers
6k views

Where is the EFI stored on the macbook and is it possible to restore a previouse 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 ...
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1answer
379 views

Why does my Mac Pro boot to black screen with third-party video card when holding Option key?

I have a Mac Pro 2012, and recently installed a new Gigabyte GTX 760 graphics/video card. I also have Windows 7 installed on this computer on my Bootcamp partition. When I attempt to start up my ...
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1answer
240 views

What is the difference between HFS+ and EFI System Partition (ESP)?

I'm familiar with manually installing certain files. In this case, I am installing rEFInd Boot Manager, see http://www.rodsbooks.com/refind/installing.html Yet when manually installing software on ...
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5k views

rEFIt boot changed after update to Yosemite

I was using rEFIt to work with Ubuntu with my Mac. After the upgrade to Yosemite I had a problem with rEFIt. I found the following solution on ubuntuforums.org but rEFIt still didn't work: cd ...
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86 views

Add an exeption to the Apple EFI (option) boot menu

I have just installed Ubuntu on a partition of my HD. I am using a MacBook Pro Mid 2012. I know that to launch Ubuntu, you need a third party EFI booter such as rEFInd. I have installed that, but I ...
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1answer
1k views

Is there any way to manually bless firmware when main disk is external?

My iMac (mid 2010) keeps pestering me to upgrade my EFI firmware to 1.8. Sadly, no matter how many times I try to to upgrade the EFI (from the manual install, or the auto update), it does not seem to ...
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0answers
59 views

Reset MacBook Pro Boot Location

I logged into my friend's MacBook Pro 13 as Guest User to install OS X Yosemite on a USB flashdrive. I downloaded the Installer from the Mac App Store and stored it somewhere within the Guest User's ...
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0answers
113 views

Upgrading a 1st Gen Macpro to 64-bit EFI

I'm still running my trusty 2006 MacPro 1,1. After various upgrades and mods which have all inexpensively helped performance no end I'm contemplating upgrading the machine's 32-bit EFI with the 64-bit ...
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377 views

Does Apple's EFI patch Thunderbolt devices to Windows 10?

So, I've been rattling with myself about this for a bit. I've followed 5SH-2a's guide of EFI Bootcamp to no avail. I decided to try it on my own, by mapping an NTFS Partition on my hard drive to a ...
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51 views

Verify the EFI firmware

I'd like to copy the EFI firmware currently installed on my MacBook Air to a file on disk, so that I can compare it with the EFI firmware on other machines. I've seen advice on reflashing the EFI ...
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1answer
5k views

Dual boot Ubuntu 14.04 on a MacBook Pro

so after a few hours of Google searching and too many headaches with a broken GPT, I've turned here. I have a 2012 MacBook Pro (9,2) that I want to dualboot OS X 10.9 and Ubuntu 14.04 on. I've read ...
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2answers
3k 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 ...
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1answer
417 views

MacBook Pro Mid 2012 Windows 8 install on SSD

I am trying to install Windows 8, efi, on my SSD. I am getting the error code: 0xC0000005 "Windows installation encountered an unexpected error. Verify that the installation sources are accesible, ...
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1answer
139 views

MacBook Pro Mid 2012 startup chime from right speaker only

After installing a ssd into my Macbook pro mid 2012 (not retina), i noticed that the startup chime is coming only from the right speaker. (I am not sure if it was always like that or if its because of ...
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1answer
217 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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3k 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 ...