FreeBSD 11.1 amd64 UEFI boot from ZFS mirror

[hanzer]

The latest FreeBSD memstick.img can boot UEFI for the installation - the video display looks nice and all seems to work well. After installation, however, no more UEFI. Is there a way to boot UEFI from a ZFS mirror on an amd64 11.1 machine?

[Head_on_a_Stick]

Disclaimer: I have zero experience with zfs and I haven't installed FreeBSD in a while.

However, I do know that to boot in UEFI mode you will need a FAT-formatted EFI system partition (type "0xEF" in the old MBR nomenclature) with FreeBSD's EFI loader placed at $ESP/EFI/BOOT/BOOTX64.EFI — any UEFI firmware should boot that loader automatically if it is found at that location.

[hanzer]

Holy crap, that sounds tedious. But, of course, many thanks for the pointer.

I wonder if the "EFI system partition (ESP)" could be a FAT formatted USB thumbdrive with some minimum set of files to get UEFI up then it redirects booting to continue from the otherwise independent ZFS-based system?

If there are any FreeBSD wizards or warriors out there who could help sort out this process, it seems like the recipe would be a nicety for other users. My system would certainly be in better shape. Without UEFI, the display is hideous; with it, the display looks pretty slick.

[Head_on_a_Stick]

Originally Posted by hanzer

Holy crap, that sounds tedious.

I last installed FreeBSD over a year ago but UEFI was handled automagically, albeit without ZFS; did the installer attempt to create an EFI system partition itself?

I wonder if the "EFI system partition (ESP)" could be a FAT formatted USB thumbdrive with some minimum set of files to get UEFI up then it redirects booting to continue from the otherwise independent ZFS-based system?

If the FreeBSD .efi loader is placed on an EFI system partition on a USB under /EFI/BOOT/BOOTX64.EFI (BOOTIA32.EFI for 32-bit systems) then your UEFI firmware should start it automatically — that is how the FreeBSD installer itself boots.

Whether the FreeBSD .efi loader will find your ZFS root on another drive is another question entirely and one that you are in a much better position to answer than I

[hanzer]

I've got to backup some data before experimenting, probably this weekend. Research suggests that it might be possible but I am still fuzzy on many of the details. For the record, and those who wish to follow, here are a few relevant data points:

https://wiki.freebsd.org/UEFI
https://lists.freebsd.org/pipermail/...st/048141.html
https://svnweb.freebsd.org/base?view...evision=294999
https://www.freebsd.org/news/status/...FI-Boot/Loader

[hanzer]

This worked! The system is a typical root on a two-disk ZFS mirror (ada0, ada1) installed from FreeBSD-11.1-RELEASE-amd64-memstick.img. After that, a USB flash drive (da0) is configured to load UEFI like this:

gpart destroy -F da0
gpart create -s gpt da0
gpart add -s 800K -t efi da0
gpart add -t freebsd-ufs da0
gpart show da0
=>      40  31260592  da0  GPT  (15G)
        40      1600    1  efi  (800K)
      1640  31258992    2  freebsd-ufs  (15G)

newfs_msdos da0p1 
newfs -t da0p2
mount -t msdosfs /dev/da0p1 /mnt
mkdir -p /mnt/efi/boot
cp /boot/boot1.efi /mnt/efi/boot/BOOTx64.efi
mkdir -p /mnt/boot
cat > /mnt/boot/loader.rc << EOF
unload
set currdev=zfs:zroot/ROOT/default:
load boot/kernel/kernel
load boot/kernel/zfs.ko
autoboot
EOF

I was very surprised this worked but it seems to be getting the job done.

Edit: I forgot to mention that the machine's BIOS was configured to boot from the flash drive (da0) in UEFI mode for this to work.