Timing issues with USB attached storage

[John Klos <john%ziaspace.com@localhost>]

Hi, all,

I run NetBSD on a number of Raspberry Pis with USB attached storage. For 
spinning rust, there's "boot_delay" in config.txt, but now I'm running in 
to another issue.

If I have a USB keyboard attached to this Pi with a Suptronics X820, it 
boots just fine. If I remove the keyboard, the SATA SSD doesn't attach 
until the kernel is already trying to mount root, so I get the error 
message seen here:

https://www.klos.com/~john/no_root.jpeg

Where is the proper place to introduce a delay so it'll discover the sd 
device before it tries to mount it as the root filesystem?

Thanks,
John Klos