dnl	$OpenBSD: prep,v 1.4 2021/07/06 18:01:34 jasper Exp $
Please be aware that OpenBSD support for this platform is far from
complete, however progress is being made.

HiFive Unmatched

Copy install{:--:}OSrev.img to a USB stick, and boot with both it and the
vendor provided uSD card (unmodified) inserted. This should enable firmware
and U-Boot to be loaded from uSD and OpenBSD bootloader and kernel to be
loaded from USB stick. At this time onboard Ethernet is not well supported,
so PCIe or USB Ethernet device will be required.

QEMU with OpenSBI and U-Boot

OpenBSD can be installed onto a disk by copying the miniroot for your
board "miniroot{:--:}OSrev.img" image to an SD card.

Booting from an SD card:

  To use the miniroot image you will need another machine to plug the
  SD card in to. Any machine type will do, as long as it supports SD card
  storage devices.  Under OpenBSD, it will appear as a ``sd'' device, for
  example sd1.

  Use the dd(1) utility to copy the miniroot to the SD card.
  The command would likely be, under OpenBSD:
  	dd if=miniroot{:--:}OSrev.img of=/dev/rsd1c bs=1m

  When you have connected the serial to your computer, a command such
  as "cu -l cuaU0 -s 115200" (assuming cuaU0 is your serial port device)
  should connect you to the board's console.

Running EFI payloads with U-Boot:

If the U-Boot target supports "distro_bootcmd" efiboot will automatically
be loaded by placing bootriscv64.efi into /efi/boot/bootriscv64.efi on a FAT
filesystem.  With dtb files placed in in /vendor/, /dtbs/vendor/, or
/dtb/current/vendor/.

If the U-Boot target supports bootefi but not automatically finding it with
"distro_bootcmd" then it must be loaded manually or by U-Boot commands or
script.
	=> run findfdt
	=> load mmc 0:1 ${fdt_addr_r} ${fdtfile}
	=> load mmc 0:1 ${kernel_addr_r} efi/boot/bootriscv64.efi
	=> bootefi ${kernel_addr_r} ${fdt_addr_r}
The bootloader will then run and try to load sd0a:/bsd off an FFS
filesystem after a timeout.