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Tags: FreeBSD, UEFI, Boot

So, I bricked my UEFI bootloader after update to 11.2-RELEASE by overwriting EFI system partition with FreeBSD bootcode ๐Ÿ˜‘, as per the instructions ๐Ÿ˜‰. Thankfully just had to enable BIOS boot, and was able to boot into OS. After that I started looking if there are any instructions to restore, or HOWTO on how to setup FreeBSD with UEFI, and turns out there are plenty of articles available online which show how to boot FreeBSD with UEFI, but apparently they use either rEFInd or some other boot manager, or my search was bad.

I installed this computer using bsdinstall(8) so I started looking into its sources, and found what I was looking into one of its script.


Make sure your drive (ada0) is partitioned as below, i.e. atleast has an EFI partition, a boot partition, and ZFS partition:

=>         40  19532873648  ada0  GPT  (XXX T)
           40       409600     1  efi  (200M)
       409640         1024     2  freebsd-boot  (512K)
       410664          984        - free -  (492K)
       411648      8388608     3  freebsd-swap  (4.0G)
      8800256  19524071424     4  freebsd-zfs  (XXX T)
  19532871680         2008        - free -  (1.0M)


  1. Setup EFI partition:

    # gpart bootcode -p /boot/boot1.efifat -i 1 ada0
  2. /dev/ada0p1 should be FAT formatted now:

    # file -s /dev/ada0p1
    /dev/ada0p1: DOS/MBR boot sector, code offset 0x3c+2, OEM-ID "BSD4.4  ", root entries 512, sectors 1600 (volumes <=32 MB), sectors/FAT 5, sectors/track 63, heads 1, serial number 0xbd4111ee, label: "EFISYS     ", FAT (12 bit), followed by FAT
  3. Setup bootcode on FreeBSD boot (freebsd-boot) partition:

    # gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 2 ada0
  4. Reboot:

    # shutdown -r now

If you’re running in RAID1 (or ZFS mirror mode), make sure to apply this change to other boot drive as well.

That’s it! ๐Ÿ˜Š