Hot answers tagged

42

First method: Ok, I booted up my UEFI box to check. First clue, near the top of dmesg. This shouldn't appear if you're booted via BIOS: [ 0.000000] efi: EFI v2.31 by American Megatrends [ 0.000000] efi: ACPI=0xd8769000 ACPI 2.0=0xd8769000 SMBIOS=0xd96d4a98 [ 0.000000] efi: mem00: type=6, attr=0x800000000000000f, range=[0x0000000000000000-...


33

If you've booted using the UEFI firmware as opposed to using BIOS firmware then your system should make the EFI NVRAM variables available in: /sys/firmware/efi/vars/ or /sys/firmware/efi/efivars/ When booting using a BIOS (or the BIOS emulation mode of UEFI firmware) then these variables aren't available. In fact, as @Santropedro pointed out, the path /...


26

Here is a way to create a Debian live USB drive with persistence. It will allow to install the missing packages which will from then on be available on every live boot using the persistence. Because we re-create the live ISO image filesystem contents on a read-write capable filesystem, we can change the bootloader configurations to enable persistence and set ...


25

I found the answer from this thread (http://ubuntuforums.org/showthread.php?t=2114055) over at ubuntuforums.org. It seems with newer Gigabyte mainboards (at least) there is a BIOS option called IOMMU Controller that is disabled by default and gives no clue or indication as to what it is for. Enabling this setting and rebooting "magically" restores all my ...


25

Fixed the efibootmgr errors by mounting the Boot variables for efibootmgr : # mount -t efivarfs efivarfs /sys/firmware/efi/efivars And then efibootmgr gave me errors about space : Could not prepare Boot variable: No space left on device Fixed that by deleting dump files : # rm /sys/firmware/efi/efivars/dump-* And then ran the usual update-grub grub-...


22

After a day of research, I can now answer my own Question: yes it is possible, and you can even use that partition as /boot and store your kernels/initramfs/etc. there. Requirements: Grub >= 2.00 (1.98 and 1.99 do not work) Grub must be installed from a Linux kernel, that has support for EFI variables (CONFIG_EFI_VARS compiled in or as module efivars) For ...


20

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 at something like this article: how-rescue-non-booting-grub-2-linux short: in this grub rescue> command line type ls ... to list all available devices, ...


18

OVMF supports -boot since r13683, and supports -kernel -append -initrd since r13923. Download OVMF-0.1+r14071-1.1.x86_64.rpm or newer version. Extract bios.bin from the rpm: rpm2cpio OVMF-0.1+r14071-1.1.x86_64.rpm | cpio -idmv Specify firmware parameter for QEMU: qemu-kvm -bios ./usr/share/qemu-ovmf/bios/bios.bin -m 1G -cdrom boot.iso (Tested with Fedora's ...


18

I'm going use the term BIOS below when referring to concepts that are the same for both newer UEFI systems and traditional BIOS systems, since while this is a UEFI oriented question, talking about the "BIOS" jibes better with, e.g., GRUB documentation, and "BIOS/UEFI" is too clunky. GRUB (actually, GRUB 2 -- this is often used ambiguously) is the bootloader ...


17

The problem was simply that the efivars kernel module was not loaded. This can be confirmed by: sh-4.2# efivar-tester UEFI variables are not supported on this machine. If you are chrooted in to your new install, exit out, and then enable efivars: exit modprobe efivars ...and then chroot back in. In my case, this means: chroot /mnt but you should ...


15

bootx64.efi doesn't get started first. Most of the time, it doesn't get started at all. The EFI firmware has its own "boot menu", analogous to the menu presented by GRUB but at an earlier stage in the boot process. Just as GRUB lets you choose which Linux kernel to run, the EFI boot menu lets you choose which EFI boot program to run — choices being things ...


14

Just drop this binary into that flash drive FAT's root directory (or maybe EFI/BOOT/ subdirectory, depends IIRC) under the name of shellx64.efi, or get yourself a copy of refind usbflash image which would also serve as a decent boot manager.


13

In my case, this helped. sudo xfs_repair -v -L /dev/dm-0 My node failed to boot after power outage and got the error "Failed to mount /sysroot" and entered into emergency mode. Mount and unmount failed so just went ahead to run with -L option and that helped my node boot up again.


11

TO ADDRESS YOUR EDIT: I didn't notice the edit to your question until just now. As written now, the question is altogether different than when I first answered it. The mirror you describe is not in the spec, actually, as it is instead a rather dangerous and ugly hack known as a hybrid-MBR partition format. This question makes a lot more sense now - it's not ...


10

Given that UEFI was only defined in 2005 there is a bunch of legacy equipment out there that doesn't support the spec. To add UEFI to a standard distribution would require testing of two code paths instead of one, and not only is boot code notoriously finicky, it's one of the most irritatingly time consuming bits of code to test.


9

This process will prevent uncertified software from booting. This may have benefits although I can't see them. You have a new security mechanism to control what can and what can not boot from your hardware. A security feature. You don't feel like you need it until it's too late. But I digress. I have read a thread on Linux mailing list where a Red hat ...


9

I just went through this with a recent laptop purchase that came with Windows 8, and UEFI secure boot. After a lot of time and research, here is what I can answer: Doesn't sound like you fit into the 'home user' category. The benefits of UEFI the average user will notice is that the first thing they see on their screen will be the Microsoft/Vendor ...


8

EDIT: When I wrote this answer very few distributions shipped with an EFI_STUB configured kernel so one had to build a custom one. Nowadays most distributions ship a suitably configured kernel and a custom build is not required any longer. In this case the sections “Set up your partitions” and “Setting things up” are the interesting ones, “Requirements” and “...


8

I found a case when I tried to use gummiboot instead of grub. Gummiboot reported an error: that it can't find kernel images. It looks like I mounted /boot and configured fstab after I installed the base system with pacstrap -i. So kernel images that were placed in a /boot directory were lost after mounting, and thus the system could not boot. I wonder what ...


8

Forget grub entirely - it is nothing but a distraction. It isn't even a boot-loader anymore; on EFI systems the bootloader is built-in to the firmware. grub is just a boot-manager in that context - and almost definitely entirely redundant. What's more - it is probably the grub install that broke everything in the first place. These are the things you need: ...


8

You can install FreeBSD alongside any linux distro with the following requirements : I want to keep the Linux GRUB and add an entry of FreeBSD to it. I want to use different SWAP partitions for Linux and BSD. I Do not want to Destroy my Linux /boot You need to create 3 partitions : swap: (4G) , /boot (512K) and the / partition. To create the ...


8

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 installed GRUB2 into the MBR (the machine is too old for EFI). I then installed NixOS, which I configured to generate grub.cfg in it's own /boot (separate from ...


7

UEFI has nothing to do with power management. ACPI manages power. UEFI indicates modern firmware than BIOS and newer platform, thus improved power efficiency. This might be a correlation. The PM subsystem is different from UEFI. Linux includes a whole range of power management functionalities, though unrelated to UEFI, like cpufreq, intel_pstate, pcie_aspm, ...


7

Measured results: BIOS - fast boot = 14.15 seconds BIOS + fast boot0 = 13.08 seconds UEFI - fast boot = 13.01 seconds [1.14 seconds faster] UEFI + fast boot0 = 11.30 seconds [1.78 seconds faster] UEFI + ultra fast1 = 10.87 seconds Even more optimizations by removing GRUB boot loader: UEFI stub + fast boot0 = 9.84 seconds UEFI stub + ultra ...


7

Thank you for flying xorriso. The problem is in the image file which you let xorriso mark as EFI System Partition. It is supposed to be a FAT filesystem image which contains a binary file named /EFI/BOOT/BOOTX64.EFI (or .../BOOTIA32.EFI for 32 bit x86) plus possibly other files. Mount the file /boot/grub/efi.img from the Ubuntu ISO for learning about its ...


7

https://superuser.com/questions/519718/linux-on-uefi-how-to-reboot-to-the-uefi-setup-screen-like-windows-8-can/1083166 Accepted answer: systemctl reboot --firmware-setup Documentation: https://www.freedesktop.org/software/systemd/man/systemctl.html#--firmware-setup


7

Later I found a posting on the Arch Linux forum, in thread "Arch fails to mount my root partition". The solution to boot Arch Linux from the emergency shell is even less typing: # mount /dev/sda2 new_root # exit


6

Change the BIOS from UEFI to legacy. When I did that, the USB appeared in the boot menu when restarting my computer.


6

The Baytrail tablets run a 64b processor and a 32b EFI, for reasons best known to Intel. Grub2 (compiled for 32b EFI) will start a 64b UEFI operating system from a 32b EFI. Just like a 64b or 32b CPU processor calling into a traditional 16b BIOS, a thunk is needed in the operating system to marshal the arguments from 64b to 32b, change the processor mode, ...


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