Question: How to boot FreeBSD head on a MACCHIATOBin (double shot)?

[Greg V]

On Mon, Oct 8, 2018 at 1:05 AM, Mark Millard via freebsd-arm 
<freebsd-arm at freebsd.org> wrote:
> Anyone willing to provide notes or instructions
> for setting up a MACCHIATOBin (double shot) to boot
> FreeBSD head from a SATA SSD? (Failing that: a USB
> storage device?) (Failing that: microsd card?)
> This could well include notes/instructions about
> what needs to be on the media that may be unique
> to the MACCHIATOBin. I realize that various things
> will not work yet. I'd just explore some of what
> does work.

 From what I remember on this mailing list, PCIe and Ethernet won't 
work.

(BTW, OpenBSD does have a PCIe driver for it already... and for the 
Rockchip RK3399 too... dang)

> Needing to have the kernel and earlier stages
> and a preliminary /etc/fstab and /boot/loader.conf
> on an microsd card but getting the UFS file system
> (/) from the SATA SSD is likely a workable combination,
> similar to what I've sometimes done on smaller
> single board computers. For such, it is the kernel
> and earlier stages where I'm unclear on the details
> for the MACCHIATOBin double shot.

According to their wiki, SATA is supported in U-Boot:
http://wiki.macchiatobin.net/tiki-index.php?page=Use+SATA+drives+in+U-Boot

You should be able to just load and run loader.efi from the drive's EFI 
System Partition.

(And USB is supported too, so you can load from a USB stick to install 
onto the SATA drive.)

If the built-in U-Boot doesn't support EFI, you can chainload a custom 
build of U-Boot with the EFI option enabled.

According to 
https://linux.debian.ports.arm.narkive.com/Co7jtx9F/debian-installer-on-arm64#post2
you can even load an EDK II (TianoCore) build from U-Boot (without 
directly flashing it).