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136 votes

GRUB starts in command line after reboot

The boot process can't find the root partition (the part of the disk, that contains the information for starting up the system), so you have to specify its location yourself. I think you have to look ...
MacMartin's user avatar
  • 2,964
52 votes

How did Linux/xBSD boot before GRUB?

The first Linux distribution I used back in the 90s (Slackware 3.0 IIRC) used LILO as a bootloader. And many distros used LILO for years even when GRUB was becoming the "default" bootloader. Moreover,...
Daniele Santi's user avatar
46 votes

"EFI\boot\bootx64.efi" vs "EFI\ubuntu\grubx64.efi" vs "/boot/grub/x86_64-efi/grub.efi" vs "C:\Windows\Boot\EFI\*"

EFI\boot\bootx64.efi: Fallback bootloader path This is the only bootloader pathname that the UEFI firmware on 64-bit X86 systems will look for without any pre-existing NVRAM boot settings, so this is ...
telcoM's user avatar
  • 101k
41 votes
Accepted

How does the kernel know it's resuming from hibernation, not booting?

Hibernation works by using a swap partition¹ to swap out all processes' memories, the kernel state, finally save some state of CPU and possibly other devices, then power off. On the way, it notes in ...
Marcus Müller's user avatar
37 votes
Accepted

Why do embedded systems need device tree while pcs don't?

Peripherals are connected to the main processor via a bus. Some bus protocols support enumeration (also called discovery), i.e. the main processor can ask “what devices are connected to this bus?” and ...
Gilles 'SO- stop being evil''s user avatar
31 votes

Why do embedded systems need device tree while pcs don't?

PCs actually do need a device tree. They just call it something else. It is not correct to say that operating systems for the descendents of PC/AT compatibles assume the existence of things such as ...
JdeBP's user avatar
  • 69.5k
30 votes

How did Linux/xBSD boot before GRUB?

LILO was the de-facto standard for booting Linux on PCs before Grub, from a very early stage (MCC, one of the first Linux distributions, used it). Various other bootloaders were used contemporaneously....
Stephen Kitt's user avatar
20 votes

Why is drive/partition number still used?

Strictly speaking, UUID is not addressing at all. Addressing is very, very simple: read drive X sector Y - or else. Read memory address Z - or else. Addressing is simple, fast, leaves not much room ...
frostschutz's user avatar
  • 49.6k
17 votes

(UEFI) Chainloading GRUB from GRUB

There's another way: you can create a menu entry that tells GRUB to load another secondary grub.cfg, such as one from another Linux distro. For example, I started with Gentoo Linux from which I ...
Emmanuel Rosa's user avatar
16 votes

Laptop boots directly to Ubuntu, can't access BIOS or Boot menu anymore

If your OS uses systemctl, you can bypass "fast boot" via the command line: sudo systemctl reboot --firmware-setup This should reboot you directly into the BIOS setup menu.
Lord Elrond's user avatar
14 votes
Accepted

Where is grub installed and do I need a new one for a separate linux installation?

Naming convention: GRUB (some of it) stays in the MBR. GRUB (rest of it) are several files that are loaded, from /boot/grub (for example: that nice image that appears as a background in GRUB is not ...
grochmal's user avatar
  • 8,707
14 votes
Accepted

What's the difference in these commands - cat piped to dd and just cat?

dd copies exactly count blocks of bs bytes, or 2880*512 bytes in total in this case(but see below). That will truncate or pad the concatenation of the two files to a fixed size (since /dev/zero gives ...
ilkkachu's user avatar
  • 141k
14 votes
Accepted

Why is drive/partition number still used?

The plain numbering scheme is not actually used in recent systems (with "recent" being Ubuntu 9 and later, other distributions may have adapted in that era, too). You are correct in observing the root ...
Hermann's user avatar
  • 6,277
13 votes

GRUB starts in command line after reboot

This is some funny thing happening to many PC dual booting with Windows 10. Happened to me and friends recently. Please note that I don't know why, I can only speculate this depends on some Windows 10 ...
alfx's user avatar
  • 231
12 votes
Accepted

PC boots straight into Windows 10 instead of launching grub

Your UEFI is booting the first thing it sees, which happens to be the Windows 10 bootloader. You should change this to GRUB/rEFInd as follows: On Windows 10, boot into UEFI settings as follows: Open ...
tstsr's user avatar
  • 158
12 votes

PKCS#7 signature not signed with a trusted key

PKCS#7 signature not signed with a trusted key This message is typically coming from a piece of hardware. In your case it's likely the Nvidia graphics card that's emitting this. This issue is ...
slm's user avatar
  • 372k
12 votes

How did Linux/xBSD boot before GRUB?

Up through mid 2.6 kernels, the x86 kernel was directly bootable if copied onto a floppy disk (as though it were a disk image). This was, in fact, the original way of booting Linux. If you look at ...
Joshua's user avatar
  • 1,893
11 votes
Accepted

After Debian installation, how to add Grub Entries for new/other bootable disks/installations?

It depends on which boot-loader was installed. If its a standard Debian install it should be GRUB2. Boot the computer with all disks containing bootable installations attached and powered. you need ...
Jenny T-Type's user avatar
10 votes

Meaning of an ampersand prefix in a device tree

From: http://developer.toradex.com/device-tree-customization Nodes can be referenced using the ampersand (&) character and the label. Overwriting properties To overwrite a property, the node ...
Xofo's user avatar
  • 659
10 votes

Where is grub installed and do I need a new one for a separate linux installation?

Just to clarify: You're using grub2, correct? In case Grub2 is installed in its own boot partition, you don't need to change anything. When it is not (which would be really strange), then you could ...
polemon's user avatar
  • 11.6k
10 votes
Accepted

What is the relation between UEFI and Grub?

1.) With EasyUEFI, you'll be editing the UEFI boot variables. These are stored in system NVRAM, just like BIOS settings. In Linux, you can edit them with the efibootmgr utility; in plain Windows, ...
telcoM's user avatar
  • 101k
9 votes

Windows boot option is missing after installing CentOS 7, how can I get it back?

I came across this issue when installing CentOS 7.0. Windows was not initially listed in the output of grub2-mkconfig. In order to install ntfs-3g as suggested in another answer, I had to first ...
clk's user avatar
  • 2,156
9 votes

EFI partition vs /boot partition

The EFI System Partition is the partition the EFI firmware (in ROM on the motherboard) knows of and from which the firmware can load EFI applications like boot loaders. So the ESP is the place where ...
Johan Myréen's user avatar
9 votes

Add Windows 10 to Grub2 bootloader

It looks like you've followed an old guide that expects Windows to use MBR partitioning. The "invalid signature" error suggests Secure Boot is enabled. When Secure Boot is enabled, all bootloaders ...
telcoM's user avatar
  • 101k
8 votes
Accepted

(UEFI) Chainloading GRUB from GRUB

I've found out how to manually install the .efi on each of my /'s. Referring to the secondary GRUB chainloader from the primary config is simple: menuentry "GRUB chainloader" { #Load grub on ...
jiggunjer's user avatar
  • 459
8 votes

PC boots straight into Windows 10 instead of launching grub

It happens because of the windows register windows boot loader as a default boot loader that's why you are not greeted with GRUB. To solve this problem, First of all create a live CD of linux. Now, ...
Sachin Tripathi's user avatar
7 votes
Accepted

When wouldn't you want to install GRUB bootloader?

When would you not want to install the GRUB bootloader? Possible reasons: You plan to boot Linux using the bootloader of another installed OS, such as Windows. You plan to boot the Linux you're ...
DepressedDaniel's user avatar
7 votes
Accepted

How does GRUB 2 work under multiple Linux partitions with UEFI

My question is, when there are multiple bootloaders (.efi) reside in ESP, are they identical? since they are all grub2. Can all of them discover all the kernel in the system? If there are multiple ...
Faheem Mitha's user avatar
  • 35.4k
7 votes

Add Windows 10 to Grub2 bootloader

You can add a custom entry to GRUB2 by editing /etc/grub.d/40_custom. If that file is already an entry for a working config, change 40 to another number that's not already used in /etc/grub.d/ [lower ...
Starbuck's user avatar
  • 171
7 votes
Accepted

GRUB changes are not applied

You should set GRUB_RECORDFAIL_TIMEOUT=0 in your /etc/default/grub then run update-grub. info -f grub -n 'Simple configuration' | less -p 'GRUB_RECORDFAIL_TIMEOUT' 'GRUB_RECORDFAIL_TIMEOUT' If ...
GAD3R's user avatar
  • 67.4k

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