Here's a quick howto of getting started with the new UEFI bootloader support in OpenBSD -current. This does assume the entire disk will be allocated by OpenBSD. Dual-booting in an UEFI setup requires extra steps which are not covered here.
By far the easiest method is to copy the
miniroot58.fs to a USB stick and boot from it. This already includes an EFI boot partition so to be sure the BIOS can correctly boot the new bootloader, start by disabling the Legacy boot option in the BIOS.
Now boot from the USB device and you should be greeted by something like:
>> OpenBSD/amd64 EFIBOOT 3.29 boot>
Boot into the RAMDISK and opt for the
(S)hell to prepare the disk with a special EFI system partition where the UEFI bootloader will be copied to after the installation.
sd0 as being the target disk:
fdisk -i -b 960 sd0
install and select the
OpenBSD option at the fdisk question. In the disklabel editor partition as usual, but leave the
i partition untouched. This is the EFI partition.
Install the sets as usual but don't reboot yet. Now, format the partition and copy the UEFI bootloader in place:
/mnt/sbin/newfs_msdos sd0i mount /dev/sd0i /mnt2 mkdir -p /mnt2/efi/boot cp /mnt/usr/mdec/BOOTX64.EFI /mnt2/efi/boot
That's it! Just reboot off the internal disk into the new UEFI bootloader.
Bonus: on some newer systems such as the Thinkpad X250 there's no
inteldrm(4) available yet, so you're stuck with
efifb(4). Instead of using the X11
VESA driver I've had better results with
Section "Device" Identifier "default device" Driver "wsfb" EndSection