Configuring GRUB for Gentoo-based Linux

1. Necessary Packages

• sys-boot/grub
• sys-fs/dosfstools
• sys-block/parted

GRUB_PLATFORMS variable for controlling target platform for grub
FILE /etc/portage/make.conf

Available options:

• efi-64, efi-32
• pc
• coreboot
• emu
• ieee1275
• loongson
• multiboot
• qemu, qemu-mips
• uboot
• xen, xen-32, xen-pvh

GRUB_PLATFORMS="efi-64"

USE for packages
FILE /etc/portage/package.use/grub

# Enabling lvm2 support if '/' is mounted as a LVM partition
sys-boot/grub device-mapper

Installing packages

emerge -avt sys-boot/grub sys-fs/dosfstools sys-block/parted

2. Necessary Disk Partition

• /boot --> /dev/sda2 --> ext4 --> 200MiB
• /boot/EFI --> /dev/sda1 --> fat32 --> 128MiB
  Or
• /boot --> /dev/sda1 --> fat32 --> 200MiB

Preparing partitions with parted, type m for help.

parted /dev/sda

Setting flat for boot partition.
Be sure the number of /boot partition is 1.

set 1 boot on
set 1 esp on

3. Formatting partitions

For those /boot & /boot/EFI is separated

mkfs.ext4 /dev/sda2
mkfs.vfat -F 32 /dev/sda1

For those ONLY has one partition for /boot

mkfs.vfat -F 32 /dev/sda1

4. Installing grub

grub-install --target=x86_64-efi --efi-directory=/boot/EFI/ --removable /dev/sda

Installing for x86_64-efi platform.
Installation finished. No error reported.

5. Installing kernel files

cd /usr/src/linux
make && make modules_install && make install

6. Generating Grub menu list

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

Troubleshooting

Volume group "rootvg" not found

Select builtin kernel modules for SCSI/SAS control
[['Cannot open root device' or 'volume group xxx not found' when booting with a Linux Kernel]]