Subject: KA670 devices: which bus?
To: None <port-vax@NetBSD.ORG>
From: Jay Maynard <firstname.lastname@example.org>
Date: 06/26/1998 17:33:29
I've gotten a cross-compile setup working, and am starting on the real work
of the KA670 port. The CPU initialization is fairly simple - if you have the
book, that is - and the SGEC device code from teh boot loader should be
fairly simple to make work in the full-blown kernel. I've got it to where it
recognizes the Qbus, and the TQK70, so now it's time to add the SGEC.
I was looking through the vsbus code, and it seems that there's a fair bit
of overhead that goes along with using it, like interrupt controllers and
such that the KA670 doesn't have. For that matter, the KA670 doesn't have
the standard vsbus devices, either.
This leads me to believe that the vsbus may not be the right place to hang
the SGEC (and, later, the SHAC) drivers. Where, then? They're not in the
Qbus address space; rather, they live in the 20080000 range that the vsbus
stuff occupies on VAXstations. There's no extra overhead, though, as there's
no CSRs that have to be manipulated beyond the device itself.