[SPARCbook] Sparcbook ATA drive formatting

[Greg]

> Unfortunately, I don't have any knowledge of the RDI line that far back,
> and I also can't be sure when Sun fixed it.

There are two requirements for being able to boot from a root partition that
uses more than the very first 2GB on the boot disk:

	- 64-bit OBP (so OBP 3.x at a minimum) since it uses 64-bit cells

	- SunOS 5.5.1 2/97 or SunOS 5.6 FCS where bug 1224425 was fixed

Even though older versions of OBP use two 32-bit cells to pass in the seek
offsets only the lower 32-bit cell is used.  Likewise in the 64-bit OBP only
the lower 64-bit cell (out of two) is used but those lower 64-bits can
address any byte on any disk you're likely to boot from.

Tadpole/RDI may have modified their 32-bit OBP to combine the two 32-bit
cells into one 64-bit signed offset for seek but I don't consider it likely.
Ian?

-greg