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Questions tagged [uefi]

The Unified Extensible Firmware Interface BIOS (UEFI) is a specification that defines a software interface between an operating system and platform firmware. UEFI replaces the Basic Input/Output System (BIOS) firmware interface originally present in all IBM PC-compatible personal computers

The Unified Extensible Firmware Interface BIOS (UEFI) is a specification that defines a software interface between an operating system and platform firmware. UEFI replaces the Basic Input/Output System (BIOS) firmware interface originally present in all IBM PC-compatible personal computers

1962 questions
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9 answers

How can I repair the Windows 8 EFI Bootloader?

I installed Windows 7 and Windows 8 in EFI mode on a hard disk some days ago. Today, the bootloader got missing/corrupted. I currently have the Windows 8 installer on a flash drive and tried using the Automatic Repair option to repair the bootloader…
Elmo
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130
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3 answers

What is the difference in "Boot with BIOS" and "Boot with UEFI"

Now Windows 8 supports the UEFI bootloader and I have read that its different from the BIOS, but it's unclear to me after many searches on the Google. Some points in mind are below:- As we all know, BIOS is an important part of accessing boot…
avirk
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104
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18 answers

If USB is not listed in BIOS as a boot option, does that mean the machine can't boot from USB?

I just purchased an Asus Zenbook Prime UX31A-DH51 with Windows 8. I want to wipe the drive and do a clean install but USB is not listed as a boot option in the BIOS. Does this mean it is not possible? Here is a photo of my BIOS options. This is the…
Chace Fields
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6 answers

Linux on UEFI - how to reboot to the UEFI setup screen like Windows 8 can?

makeuseof.com explains that Windows 8 certified hardware has a new way to enter the UEFI setup screen (equivalent to BIOS). From How To Access The BIOS On A Windows 8 Computer: No longer do we press a certain key during the boot process to reveal…
sourcejedi
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2 answers

Stuck on UEFI interactive shell with Mac OS X High Sierra VM

I got a Mac OS X virtual machine on VirtualBox and when I started it, I got into this UEFI shell: What should I do?
WeakMaster
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8 answers

How to reinstall GRUB2 EFI?

After successfully updating my bios, something went wrong and I ended up with a blinking cursor on the top left corner of a black screen. No errors, no nothing. The bios now only listed a SATA:  boot option in place of the usual UEFI…
Maxime R.
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1 answer

EFI Partition vs /boot partition

I have just sat down to install debian 7, which contains something called 'EFI' which is entirely new to me. I went through the install as I usually do; 256MB /boot partition, bootable, unencrypted Remaining disk size as / partition, encrypted The…
lynks
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50
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2 answers

What is CSM option

What is the CSM option in BIOS? If I can't boot into Windows any more, is it because CSM is disabled? Would an ASUS K55 come with this option diabled?
Ken
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49
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1 answer

If I buy a computer with Windows 8 and Secure Boot, will I still be able to install Linux?

I've heard a lot about how Microsoft is implementing UEFI Secure Boot in Windows 8. Apparently it prevents "unauthorized" bootloaders from running on the computer, to prevent malware. There's a campaign by the Free Software Foundation against secure…
nhinkle
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1 answer

Windows detects GPT disk as MBR in EFI boot

This disk is OCZ VERTEX 128GB SSD. It is formatted as GPT from OSX. The disk layout is, /dev/disk1 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *128.0 GB …
Sarim
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40
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8 answers

How to make UEFI bios start GRUB, not Windows?

The TL;DR, added in the edit: The question is: How can I make the BIOS prefer GRUB over Windows Boot Manager on the same UEFI boot partition? The problem is not with Grub; Grub does the right thing when the BIOS starts it. The problem is not with…
Jon Watte
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4 answers

What is the absolute minimum size a UEFI system partition can be?

Suppose I have a flash drive, and I want it to be bootable. Suppose I also have a basic EFI file which will accomplish something. So, what is the minimum size the ESP can be? I've read that it's 100MB, but that seems to be specifically in regards to…
MazeOfEncryption
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35
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5 answers

What exactly is "UEFI with CSM" boot mode?

Under this question, I was told that "UEFI with CSM" is essentially BIOS mode. It made me quite confused because what I've learnt over the years is far from that. As per my observation, I think CSM is a special mechanism that allows previous "not…
iBug
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How to delete OS from boot menu

After installing fedora and Centos and other OS now I have them all showing in my Boot menu [F2] on start up not the menu form the OS even after deleting them and reinstaling other OS - Ubuntu -so It just shows one when the OS starts but when I go…
Talal
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2 answers

Why does Windows 10 use a separate 100MB partition for UEFI since with UEFI it can read in the filesystem in C:\Windows\System32\winload.efi?

What I've read from UEFI so far is that it has features that BIOS didn't have: it can look in the filesystem and find the boot loader there. Then, since the UEFI boot system can read directly C:\Windows\System32\winload.efi from the main partition…
Basj
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