Booting from USB on RPi3

[bob prohaska]

On Tue, Apr 21, 2020 at 07:31:40AM +1200, Jonathan Chen wrote:
> 
> This is how I got my RPI3 running 12-STABLE to boot off USB. It does
> require a microSD card with u-boot, and the loader.efi built sometime
> after Sep 2019 though. However, my root-filesystem (and swap) lives on
> an external USB drive.
> 
> 1. Copy the loader.efi to EFI/BOOT/bootaa64.efi
> 
> 2. Create a text file: EFI/FreeBSD/loader.env, this file contains a
> one-line directive to loader(8) on where to find a kernel to boot.
> Mine contains:
>   rootdev=disk1p1:
> The disk entry should be the same as what loader(8) expects with your
> USB disk setup. Mine has a GPT partitioning scheme, with the root-fs
> on partition-1.
> 
> 3. All /etc/fstab entries should use symbolic name entries instead of da0*. eg:
> 7:27am# cat /etc/fstab
> # Device                Mountpoint      FStype  Options         Dump    Pass#
> /dev/gpt/topaz-root     /               ufs     rw              1       1
> /dev/gpt/topaz-swap     none            swap    sw              0       0
> 
> Hope this helps.
> -- 

Where is the kernel loading from? I gather it's been long-time
practice to load the kernel from microSD and then mount the USB
device as root; it that what you're doing? It appears that using
usbboot (correctly!) would eliminate that extra step.

Thanks for writing!

bob prohaska