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Date: Thu, 3 Jul 1997 19:22:56 +0200
From: Stefan Esser <se@freebsd.org>
To: SAKIYAMA Nobuo <nobuo@mx2.meshnet.or.jp>
Cc: FreeBSD-tech-jp@jp.freebsd.org, Stefan Esser <se@freebsd.org>
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Subject: [FreeBSD-tech-jp 302] Re: Question about Ultra support in NCR driver of FreeBSD
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On Jul 3, SAKIYAMA Nobuo <nobuo@mx2.meshnet.or.jp> wrote:
> Hi, I am a new user of FreeBSD (2.2.2-RELEASE).

Hi!

> My system has DC-390U and Quatum FBTMs,
> but I found that your NCR driver does not support Ultra SCSI.
> A version in the FreeBSD-current has the similar limitation.

Yes, I know ...

> I sought the Web, and I found your driver is ported to the Linux,
> and updated for the support of Ultra-SCSI, and integrated into
> Linux 2.1.43 (current development version), and Linux 2.0.30 (next 
> stable version). Newest driver is located in
> 
> ftp://linux.wauug.org/pub/roudier/

Yes. Gerard ported the driver to Linux, and was
very interested in implementing a few missing 
features (like Ultra support). I know his code,
and I seem to remember, that I send him a few
diffs that prepared the ground, half a year back.

> Now, I am planning to port the linux version back to the FreeBSD,
> but if you are going to port it back by yourself,

Well, there were two reasons not to put the 
Ultra-SCSI support into FreeBSD:

1) I don't think there are many systems that 
   really can take advantage of Ultra-SCSI,
   today. (Yes, I got an Ultra-Wide drive for
   testing, myself, they exsit. But you will 
   not see much of a difference in performance 
   except if there are many drives on one SCSI 
   bus.)

2) At the time when the 53c875 changes went 
   into the driver (end of 1996), the generic 
   SCSI code was about to be replaced. I was
   waiting for a final version of this code.
   But Justin Gibbs decided to go for a CAM
   interface instead of his previous concept,
   which is quite some additional work, and 
   should be available anytime soon. The new
   interface will require quite some changes 
   to the driver, and I'd rather redesign the
   parts that are affected to better support
   high SCSI rates (beyond the 20MHz of the
   53c875, the 53c895 will do up to 40MHz).

> I can enjoy my short summer vacation:)

Well, I just (July 1st) started to work on a new 
project, which currently means I got no spare
time (and can't think of having a vacation for 
the next few months).

> Please comment what I shuld do.

Well, if you want to hack on this, just do it.
I know the changes that have to be done, and 
could merge them in easily, if I took a weekend
off. (May be able to this, since my son *will*
be on a vacation :)

I had implemented some of the planned cleanup
in a local copy of the driver, when I ran out 
of time at the end of last year. In fact, I'd
prefer if that modified version became the base
of the code that gets extended for Ultra, since
it will definitely be easier. (I removed some
assumptions of the original driver, which don't
hold anymore, but can be worked around, as Gerard
proved ... :)

Regards, STefan
