When you delete your Windows partition from your Mac manually, it leaves its EFI Boot entry. Let's get rid of that, shall we? Getting Rid of the Windows EFI Boot Entry. The Mac Observer's. If the EFI partition is damaged, Mac system will malfunction in many aspects, such as system failure to boot up, etc. In a nutshell, broken EFI partition will cause lots of troubles. You’d better resolve it as soon as possible. This article will give you a quick guide. New to hackintoshing? In this article we'll show you how to mount your EFI partition on macOS, which will assist you in one of the steps needed to get your new system up and running. Connect with EFI Experts and Fiery Users. Ask questions about EFI products, receive updates about new releases, find important product updates. EFI Communities, the new EFI support platform, to connect, share, learn, and browse through our Knowledge Base Articles, Forum Posts and How-to guides.
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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 the boot drive as 'EFI Boot' (when I pressed the options key to select the boot drive).
In the part when I had to format my partitions for installation, Windows created 2 partitions in the free space: 1. the Microsoft Reserved partition and 2. the partition where Windows is meant to be installed.
The installation went well, no errors were raised, but when I pressed the options key at startup to boot to Windows, my Mac recognized my Windows partition as 'EFI Boot' (so now I have 3 options when I pressed the Options key:Macintosh HD, EFI Boot, and Recovery).That is not really a big problem to me, but then when I started using Windows, I couldn't find a way to make the audio drivers working. I couldn't install Microsoft Office either.
So, I booted into my Macintosh HD partition, and use disk utility to remove the Windows partition and the Microsoft Reserved partition. Then, I reinstalled Windows 8.1 by following these instructions: Boot camp install of Windows 7 issue, no bootable devices
Everything went well and the audio is now working, but now, when I press the Options key at startup, I have 4 options: Macintosh HD, Windows, EFI Boot, and Recovery. When I tried choosing 'EFI Boot', it shows me a blue screen, saying:
Recovery
Your PC needs to be repaired
A required device isn't connected or can't be accessed.
Press Enter to try again
Press F8 for Startup settings
Your PC needs to be repaired
A required device isn't connected or can't be accessed.
Press Enter to try again
Press F8 for Startup settings
When I tried pressing Enter and F8 keys, it returned to the same blue screen.
When I tried mounting the EFI partition, I see 3 folders: Apple, Boot, and Microsoft. I tried deleting the Microsoft folder (and I kept the copy of it somewhere else), and boot into the EFI Boot again, my computer froze and restarted.
The question is, how can I make the EFI Boot disappear when I press the options key at startup? It's not creating any problems with my Mac or Windows partitions, but I'm very curious about what it actually is, what does it have to do with my computer, and why does it decide to show up when I pressed the options key?
Community♦
user33003
1 Answer
Your question has two parts. The first part is repeated below.
The question is, how can I make the EFI Boot disappear when I press the options key at startup?
This a duplicate of the question 'Ghost partition, Windows BSOD'. The rest of your question, which again is repeated below, does require further explanation.
It's not creating any problems with my Mac or Windows partitions, but I'm very curious about what it actually is, what does it have to do with my computer, and why does it decide to show up when I pressed the options key?
The 'EFI Boot' appears because the Mac firmware finds the boot file
BOOTx64.EFI
in the folder EFIBOOT
on the EFI partition of your internal drive. This is part of the UEFI specification. For example, if you go to the 'uefi.org Specifications web page', you can download and view the 'UEFI Specification Version 2.5'. Sections 3.5.1.1 Removable Media Boot Behavior and 3.5.1.2 Non-removable Media Boot Behavior (on pages 88-90) describe the naming of the BOOTx64.EFI
file and that it should appear in the EFIBOOT
folder.When holding down the Option ⌥ at startup, the Mac firmware will look for the
EFIBOOTBOOTx64.EFI
file on each EFI partition of all drives accessible at startup. Each occurrence will generate an icon with the label 'EFI Boot' on the Startup Manager menu.When Windows installs, some of the startup files are stored in the folder
EFIMICROSOFT
. These files are also duplicated (with some renaming) in the EFIBOOT
folder. Not all non-Apple operating systems do this when installing. For example, Ubuntu Linux does not. (Well, last time I installed in EFI mode it did not.) The Ubuntu installer does create a folder EFIUBUNTU
with startup files (GRUB), which the Mac firmware by default ignores. To get Ubuntu to appear in the Startup Manager, you have to manually mount the EFI partition and copy the files in the EFIUBUNTU
folder to the EFIBOOT
folder. (Also, the copied grubx64.efi
file needs to be renamed to BOOTX64.EFI
.)If you need to do this for two operating systems, then you will need a second EFI partition. This should not present a problem since an EFI partition is fairly small (<200 MB) and the limit on Macs by default is 128 partitions. However, to tell one operating system for the other, while viewing the choices presented by the Startup Manager, you may want to change the icons.
For example, I have rEFInd installed in a second 134 MB EFI partition on my iMac. (This happens to be the last of 9 partitions.) Additionally, I have Windows 10, Yosemite (on volume 'Steelhead') and El Capitan (on volume 'Steelhead2') installed. Below is a image of my Macs Startup Manager menu. (For a better view, click on the image or open in a new window.)
The icon can be changed by mounting the EFI partition and adding the icon file
.VolumeIcon.icns
to the root folder. A collection of these icons, for popular Linux and other operating systems, can be found here.Community♦
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(Redirected from EFI System partition)
The EFI (Extensible Firmware Interface) system partition or ESP is a partition on a data storage device (usually a hard disk drive or solid-state drive) that is used by computers adhering to the Unified Extensible Firmware Interface (UEFI). When a computer is booted, UEFI firmware loads files stored on the ESP to start installed operating systems and various utilities.
An ESP contains the boot loaders or kernel images for all installed operating systems (which are contained in other partitions), device driver files for hardware devices present in a computer and used by the firmware at boot time, system utility programs that are intended to be run before an operating system is booted, and data files such as error logs.[1]
- 2Usage
Overview[edit]
The EFI system partition needs to be formatted with a file system whose specification is based on the FAT file system and maintained as part of the UEFI specification; therefore, the file system specification is independent from the original FAT specification.[2][3] The globally unique identifier (GUID) for the EFI system partition in the GUID Partition Table (GPT) scheme is C12A7328-F81F-11D2-BA4B-00A0C93EC93B, while its ID in the master boot record (MBR) partition-table scheme is 0xEF. Both GPT- and MBR-partitioned disks can contain an EFI system partition, as UEFI firmware is required to support both partitioning schemes. Also, El Torito bootable format for CD-ROMs and DVDs is supported.[1]
UEFI provides backward compatibility with legacy systems by reserving the first block (sector) of the partition for compatibility code, effectively creating a legacy boot sector. On legacy BIOS-based systems, the first sector of a partition is loaded into memory and execution is transferred to this code. UEFI firmware does not execute the code in the MBR, except when booting in legacy BIOS mode through the Compatibility Support Module (CSM).[1]
Mount Efi On Macos
The UEFI specification requires MBR partition tables to be fully supported.[1] However, some UEFI implementations immediately switch to the BIOS-based CSM booting upon detecting certain types of partition table on the boot disk, effectively preventing UEFI booting to be performed from EFI system partitions contained on MBR-partitioned disks.[4]
UEFI firmware supports booting from removable storage devices such as USB flash drives. For that purpose, a removable device needs to be formatted with a FAT12, FAT16 or FAT32 file system, while a boot loader needs to be stored according to the standard ESP file hierarchy, or by providing a complete path of a boot loader to the system's boot manager.[1]
Usage[edit]
Linux[edit]
GRUB 2 and elilo serve as conventional, full-fledged standalone UEFI boot managers for Linux. Once loaded by a UEFI firmware, they both can access and boot kernel images from all devices, partitions and file systems they support, without being limited to the EFI system partition.
EFI Boot Stub makes it possible to boot a Linux kernel image without the use of a conventional UEFI boot loader. By masquerading itself as a PE/COFF image and appearing to the firmware as a UEFI application, an x86 kernel image with EFI Boot Stub enabled can be directly loaded and executed by a UEFI firmware. Such kernel images can still be loaded and run by BIOS-based boot loaders; thus, EFI Boot Stub allows a single kernel image to work in any boot environment.[5]
Linux kernel's support for the EFI Boot Stub is enabled by turning on option
CONFIG_EFI_STUB
(EFI stub support) during the kernel configuration.[6] It was merged into version 3.3 of the Linux kernel mainline, released on March 18, 2012.[7]Gummiboot (a.k.a. systemd-boot) is a simple UEFI boot manager that loads and runs configured UEFI images, accessing only the EFI system partition. Configuration file fragments, kernel images and initrd images are required to reside on the EFI system partition, as Gummiboot does not provide support for accessing files on other partitions or file systems. Linux kernels need to be built with CONFIG_EFI_STUB
enabled so they can be directly executed as UEFI images.[8]The mount point for the EFI system partition is usually
/boot/efi
, where its content is accessible after Linux is booted.[9]Efi On Mac
MacOS[edit]
On MacOS computers based on the x64 hardware architecture, the EFI system partition is initially left blank and unused for booting.[10] However, the EFI system partition is used as a staging area for firmware updates.[11]
The system will still boot after the EFI partition is deleted, in which case the boot manager will allow users to choose whether to start a Boot Camp partition or the default Mac OS X, but firmware updates will fail.[citation needed].
Windows[edit]
Microsoft recommends that when partitioning a disk, the EFI system partition be the first partition on the disk.[12] This is not a requirement of the EFI specification itself. On Windows XP 64-Bit Edition and later, access to the EFI system partition is obtained by running the mountvol /s command.
An ESP drive may temporarily be created if your Windows system is pending a restart after a Windows Update. This is to allow the computer to startup in the Windows Update environment (mini OS) so there are no competing applications during the update. This drive, and corresponding space, should be returned to its host drive (the actual physical drive) upon completion of the update. The older computers don't properly support the editing of EFI partitions.
TrueOS (a BSD operating system)[edit]
Efi Lock On Mac
TrueOS' UEFI support (for amd64 only) has been added to the installer and the boot manager since version 10.1 with the default EFI boot manager to be rEFInd.[13] This includes ACPI detection and setup of Root System Description Pointer (RSDP),[14] eXtended System Descriptor Table (XSDT),[15] and Root System Description Table (RSDT)[16] pass-through values to the kernel. A new installation is needed in order to install UEFI support as it requires the creation of a small FAT partition. The current UEFI does not support secure boot.
See also[edit]
References[edit]
- ^ abcde'UEFI Specifications (versions 2.5 and older)'(PDF). UEFI.org. April 2015. Retrieved 2015-05-29.
- ^'UEFI Specification Version 2.5, Section 12.3 File System Format'(PDF). UEFI.org. April 2015. pp. 536, 537. Retrieved 2015-05-29.
The file system supported by the Extensible Firmware Interface is based on the FAT file system. EFI defines a specific version of FAT that is explicitly documented and testable. Conformance to the EFI specification and its associate reference documents is the only definition of FAT that needs to be implemented to support EFI. To differentiate the EFI file system from pure FAT, a new partition file system type has been defined.
- ^'Technical Note TN2166: Secrets of the GPT'. Developer.Apple.com. 2006-11-06. Retrieved 2015-05-06.
- ^'UEFI system booting from MBR partition table and GRUB legacy'. ArchLinux.org. June 2012. Retrieved 2013-10-06.
- ^'Linux kernel documentation: Documentation/efi-stub.txt'. Kernel.org. 2014-06-16. Retrieved 2014-11-26.
- ^'Linux kernel 3.11.1 arch/x86/Kconfig: CONFIG_EFI_STUB (line #1575)'. Kernel.org. Retrieved 2013-10-06.
- ^'Linux kernel 3.3: 1.10. EFI boot support'. KernelNewbies.org. 2012-03-18. Retrieved 2013-10-06.
- ^'gummiboot: Simple UEFI Boot Manager'. FreeDesktop.org. Archived from the original on 2013-09-12. Retrieved 2016-01-22.
- ^'UEFI - Community Ubuntu Documentation'. Ubuntu.com. 2013-12-21. Retrieved 2013-12-27.
- ^'rEFIt: Myths and Facts About Intel Macs – Myth: Mac OS X Requires a Hidden EFI System Partition'. rEFIt.SourceForge.net.
- ^'Firmware updates for Intel-based Macs require a GUID partition scheme'. Apple Knowledgebase.
- ^'EFI System Partition'. Windows and GPT FAQ. Archived from the original on 9 March 2009.
- ^'What's New in 10.1'.
- ^RSDP
- ^XSDT
- ^RSDT
External links[edit]
- EFI System Partition Subdirectory Registry – A registry of the subdirectories that lie below the
/EFI
directory on an EFI system partition
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