DSSI support for NetBSD: request for docs.

From: Johnny Billquist <bqt_at_update.uu.se>
Date: Wed Feb 27 05:03:49 2002

On Wed, 27 Feb 2002, Jochen Kunz wrote:

> On 2002.02.27 05:04 Gunther Schadow wrote:
>
> > I have the UDA50 manual
> Do you have a scanner? ;-)

I would really like to get my hands on the UDA50 programming manual. It
seems to be extremely rare.

> > (BTW: anyone have a UDA50?)
> Aha. The 11/780 demands its tribute. ;-)

:-) I have a bunch of UDA50, both for my PDP-11s, and for the 8650.

> > I would assume that peeking into the Ultrix 4.2
> > source code could be of great help.
> This may lead to serious copyright problems, even with a "cleanroom
> reverse engineering approach". I think BSD has suffered enough from such
> problems. Additionaly Ultrix may be that different, that it may be
> easier to write somthing new from scratch, than port ancient Ultrix code
> to NetBSD.

True about the copyright problems.
However, the Ultrix driver is a beautiful beast. When you declare an MSCP
disk, you don't say where it's located. You just say:
disk ra<x> at mscp drive <y>

Controllers are declared as:
controller uda0 at uba0
controller uq0 at uda0
controller hsc0 at ci0

And then the disks can be either at hsc0 or uq0, and you can move them
without problems.
DSSI is yet another, and so on...

This nice solution comes from the fact that Ultrix divided the driver into
two parts (as does all DEC OSes), the class driver and the port
driver. The class driver handles all mscp disks, no matter how they are
connected to the system. The port driver handles the passing of the
physical messages between the controller and the system. Port drivers are
individual for each type of hardware. Port drivers can also be used by
other stuff than MSCP, such as DUP, TMSCP, or IP for that matter.

> > However, I thought that NetBSD already supports RA disks, so,
> > the MSCP protocol should be there.
> Yes. NetBSD has already MSCP drivers. But guessing a bus protocol on
> bais of a device driver is somewhat painful. Also guessing is no good
> bais for new code.

True. And also, the NetBSD RA support have some bug in it, along with
being very much tied to the UDA50/KDA50 right now.

        Johnny

Johnny Billquist || "I'm on a bus
                                  || on a psychedelic trip
email: bqt_at_update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
Received on Wed Feb 27 2002 - 05:03:49 GMT