Argthtjtr

I need a Gentoo 13 machine to test some software on the platform. I'm not a Gentoo regular, so I'm suffering their install procedures. I'm at
Configuring the bootloader | Installing GRUB2, and it failed with:

# grub2-install --target=x86_64-efi --efi-directory=/boot

Installing for x86_64-efi platform.

grub2-install: error: /boot doesn't look like an EFI partition.

I backtracked to Preparing the disks | Default: Using parted to partition the disk, and it appears I have things setup as instructed:

(chroot) Gentoo-2012 / # parted

GNU Parted 3.2

Using /dev/sda

Welcome to GNU Parted! Type 'help' to view a list of commands.

(parted) unit mb                                                          

(parted) print                                                            

Model: ATA VMware Virtual I (scsi)

Disk /dev/sda: 21475MB

Sector size (logical/physical): 512B/512B

Partition Table: gpt

Disk Flags: 



Number  Start   End      Size     File system     Name    Flags

 1      1.05MB  3.15MB   2.10MB                   grub    bios_grub

 2      3.15MB  131MB    128MB    ext2            boot    boot, esp

 3      131MB   2572MB   2441MB   linux-swap(v1)  swap    msftdata

 4      2572MB  21474MB  18902MB  ext4            rootfs  msftdata

The results above are from the same chapter of the manual, sections Applying a filesystem to a partition and Activating the swap partition.

I also followed the comment EFI directory should not be /boot but /boot/efi from Bootloader problems and questions on the Gentoo forums, but it resulted in the same error:

(chroot) Gentoo-2012 / # mkdir /boot/efi

(chroot) Gentoo-2012 / # grub2-install --target=x86_64-efi --boot-directory=/boot --efi-directory=/boot/efi

Installing for x86_64-efi platform.

grub2-install: error: /boot/efi doesn't look like an EFI partition.

What's the problem and how do I fix it?

Here's the corresponding fdisk view of the information presented by gparted above.

(chroot) Gentoo-2012 / # fdisk -l

Disk /dev/loop0: 3.3 GiB, 3567640576 bytes, 6968048 sectors

Units: sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes    



Disk /dev/sda: 20 GiB, 21474836480 bytes, 41943040 sectors

Units: sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disklabel type: gpt

Disk identifier: 52F5571A-808B-XXXX-XXXX-XXXXXXXX



Device       Start      End  Sectors  Size Type

/dev/sda1     2048     6143     4096    2M BIOS boot

/dev/sda2     6144   255999   249856  122M EFI System

/dev/sda3   256000  5023743  4767744  2.3G Microsoft basic data

/dev/sda4  5023744 41940991 36917248 17.6G Microsoft basic data

I also verified the package sys-boot/grub supports EFI:

(chroot) Gentoo-2012 / # cat /etc/portage/make.conf | grep GRUB

GRUB_PLATFORMS="emu efi-32 efi-64 pc"

I then performed an emerge --ask --newuse sys-boot/grub, emerge -pv sys-boot/grub, and then rebuilt grub.

The answer is simple. EFI System Partition (ESP) should be FAT32 (FAT16 or even FAT12 will also do for most proper UEFI; they are mostly shown as vfat in Linux) instead of ext2:

mkfs.fat -F32 /dev/sda2

FWIW, if you are not going to install grub i386-pc (for BIOS/CSM boot), you don't need the "BIOS boot" partition. It is only required by grub i386-pc (but not grub x86_64-efi or i386-efi) on GPT.

It doesn't really matter whether you use the ESP for /boot. If you do, you should run:

grub2-install --efi-directory /boot

If you mount it on /boot/efi instead, then you should run:

grub2-install --efi-directory /boot/efi

--boot-directory /boot is implied (i.e. default); It doesn't matter whether /boot is the ESP, another separate partition, or a directory on the / filesystem.

You may not even need to chroot again to perform grub2-install; For example, you mounted sda4, your partition for /, on /mnt; AND THEN, mounted sda2, your ESP, on /mnt/boot/efi, then you can simply run:

grub2-install --boot-directory /mnt/boot --efi-directory /mnt/boot/efi

Although grub2-mkconfig needs to be run in chroot AFAIK. But if you plan on writing a simple and clean grub.cfg yourself instead (which is the only graceful way to use grub2), then this will be out of your concern.

The problem seemed to be mixing and matching BIOS, EFI, MBR, and GPT. I tried to follow the guides and use the GPT, but there were some dependencies that I could not resolve because I am too inexperienced. Its not even clear to me the kernel was built with GPT support (via config option CONFIG_EFI_PARTITION).

When I dropped GPT and EFI and switched to purely BIOS and MBR, I was able to boot the resulting machine. BIOS and GPT are supposed to be a valid combination, but I'm wondering if it works in practice (see, for example, Bootloader Options).

Here's the configuration I was able to run the machine with:

$ parted

GNU Parted 3.2

Using /dev/sda

(parted) print                                                            

Model: ATA VMware Virtual I (scsi)

Disk /dev/sda: 21.5GB

Sector size (logical/physical): 512B/512B

Partition Table: msdos

Disk Flags: 



Number  Start   End     Size    Type     File system     Flags

 1      1049kB  135MB   134MB   primary  ext2            boot

 2      135MB   19.5GB  19.3GB  primary  ext4

 3      19.5GB  21.5GB  2012MB  primary  linux-swap(v1)

Partition 1 is /boot, Partition 2 is /, and Partition 3 is swap.

I just had this issue and found that /boot existed but didn't have my boot partition mounted to it. Just had to mount the boot partition to fix this

mnt /dev/sda1 /boot