Booting RasPi3 to SSD via SD card

This started as an issue, but think it wise to keep this information around past closing the issue:

brianthetall commented 23 hours ago I'm trying to boot from SD to USB harddisk.

I found this line inside the kernel source, which looks like it would do the trick. However there is no "RPI3" version of this file. How does one change the device to be used to load the kernel for a RPI3?

/src/sys/arm/conf/RPI2: options ROOTDEVNAME="ufs:mmcsd0s2"

brianthetall commented 7 minutes ago Still not what I need, but I have found that removing the UFS partition from the SD card causes the system to boot to a loader prompt. From there I can specify ufs:/dev/da0s2a; the SSD then boots as root! ....But really need this to happen automatically...

keithmj114 commented 28 seconds ago Manually boot into the SSD as root and edit /etc/fstab to point its root directory to /dev/"SSD ID". Crochet automatically sets root to mount an SD card, changing this fixed the problem.