GRUB

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GRUB is a multi-boot bootloader that is installed by default on most Linux distributions. Here's a quick breakdown on getting it working with Arch Linux.

Install the package

pacman -S grub

package details - grub


If you're on UEFI, install efibootmgr as well.

pacman -S efibootmgr

package details - efibootmgr



Install the bootloader

UEFI

Create a partition in the first 2TB of your drive. This partition must be FAT and at least 100MB. The partition table of the disk must be GPT and the partition should be set as an EFI System Partition. Mount this partition under /boot/efi/. Install the bootloader to this EFI partition by executing the following command:

grub-install --target=x86_64-efi --efi-directory=/boot/efi/ --bootloader-id=Arch


BIOS

Create a partition for /boot/ in the first 2TB of your disk (ext4 is fine). Set this partition to Active so it will be used for booting.

Install GRUB to the disk by executing the following command, replacing /dev/sdX with your disk's location:

grub-install --target=i386-pc /dev/sdX


Microcode

With vulnerabilities like Spectre and Meltdown lingering, one should strive to stay up-to-date on their loaded microcode. Arch Linux provides the latest packages from both AMD and Intel, and GRUB will automatically load the required microcode before the Linux kernel.

AMD ucode

To install the latest AMD microcode, run the following:

pacman -S amd-ucode

package details - amd-ucode

Intel ucode

To install the latest Intel microcode, run the following:

pacman -S intel-ucode

package details - intel-ucode




Generate the config file

After the bootloader has been installed we need to generate the main configuration file /boot/grub/grub.cfg.

grub-mkconfig -o /boot/grub/grub.cfg

This will need to be performed each time you manually switch kernels (not automatic updates - this is auto-performed). If you uninstall the previously configured kernel without generating a new config file you risk having a non-booting machine. To recover from this state, boot into an Arch Live installer and mount your disks like you did during Installing Arch, then run the above command in your arch-chroot. This should generate a working configuration you can then reboot into.



Troubleshooting

Device /dev/xxx not initialized in udev database even after waiting 10000000 microseconds

If grub-mkconfig hangs and gives error: WARNING: Device /dev/xxx not initialized in udev database even after waiting 10000000 microseconds

You may need to provide /run/lvm/ access to the chroot environment using:

mkdir /mnt/hostlvm
mount --bind /run/lvm /mnt/hostlvm
arch-chroot /mnt
ln -s /hostlvm /run/lvm

See FS#61040 and workaround.