buildroot

config BR2_TARGET_GRUB2

    bool "grub2"

    depends on BR2_i386 || BR2_x86_64

    help

      GNU GRUB is a Multiboot boot loader. It was derived from

      GRUB, the GRand Unified Bootloader, which was originally

      designed and implemented by Erich Stefan Boleyn. GRUB 2 has

      replaced what was formerly known as GRUB (i.e. version

      0.9x), which has, in turn, become GRUB Legacy.

​

      Amongst others, GRUB2 offers EFI support, which GRUB Legacy

      doesn't provide.

​

      Notes on using Grub2 for BIOS-based platforms

      =============================================

​

      1. Create a disk image

         dd if=/dev/zero of=disk.img bs=1M count=32

      2. Partition it (either legacy or GPT style partitions work)

         cfdisk disk.img

          - Create one partition, type Linux, for the root

        filesystem. The only constraint is to make sure there

        is enough free space *before* the first partition to

        store Grub2. Leaving 1 MB of free space is safe.

      3. Setup loop device and loop partitions

         sudo losetup -f disk.img

         sudo partx -a /dev/loop0

      4. Prepare the root partition

         sudo mkfs.ext3 -L root /dev/loop0p1

         sudo mount /dev/loop0p1 /mnt

         sudo tar -C /mnt -xf output/images/rootfs.tar

         sudo umount /mnt

      5. Install Grub2

         sudo ./output/host/usr/sbin/grub-bios-setup \

            -b ./output/host/usr/lib/grub/i386-pc/boot.img \

            -c ./output/images/grub.img -d . /dev/loop0

      6. Cleanup loop device

         sudo partx -d /dev/loop0

         sudo losetup -d /dev/loop0

      7. Your disk.img is ready!

​

      Using genimage

      --------------

​

      If you use genimage to generate your complete image,

      installing Grub can be tricky. Here is how to achieve Grub's

      installation with genimage:

​

      partition boot {

          in-partition-table = "no"

          image = "path_to_boot.img"

          offset = 0

          size = 512

      }

      partition grub {

          in-partition-table = "no"

          image = "path_to_grub.img"

          offset = 512

      }

​

      The result is not byte to byte identical to what

      grub-bios-setup does but it works anyway.

​