From owner-freebsd-hardware  Tue Sep  9 10:26:47 1997
Return-Path: <owner-freebsd-hardware>
Received: (from root@localhost)
          by hub.freebsd.org (8.8.7/8.8.7) id KAA21823
          for hardware-outgoing; Tue, 9 Sep 1997 10:26:47 -0700 (PDT)
Received: from biggusdiskus.flyingfox.com (biggusdiskus.flyingfox.com [206.14.52.27])
          by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id KAA21809
          for <freebsd-hardware@FreeBSD.ORG>; Tue, 9 Sep 1997 10:26:42 -0700 (PDT)
Received: (from jas@localhost)
	by biggusdiskus.flyingfox.com (8.8.5/8.8.5) id KAA02502;
	Tue, 9 Sep 1997 10:23:11 -0700 (PDT)
Date: Tue, 9 Sep 1997 10:23:11 -0700 (PDT)
From: Jim Shankland <jas@flyingfox.com>
Message-Id: <199709091723.KAA02502@biggusdiskus.flyingfox.com>
To: jkh@time.cdrom.com
Subject: Re: four-port ethernet - adaptec ANA-6944A/TX
Cc: freebsd-hardware@FreeBSD.ORG
Sender: owner-freebsd-hardware@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

Jordan writes: 

> 	http://www.3am-software.com/de-970703.tar.gz
> 
> We're trying to evaluate that driver now for possible inclusion
> with the next FreeBSD release(s).

Note that that version of the driver has a fairly serious bug in
FreeBSD:  it mallocs the tulip_softc structure, which has grown
to > 4 KB in size.  At the end of the tulip_softc structure are
arrays of receive and transmit descriptors that must be physically
contiguous.  Since the structure spans a page boundary, they may
not turn out to be contiguous.

Matt's suggested solution was to reduce TULIP_TXDESCS (the number
of transmit descriptors) from 128 to 32; this shrinks the tulip_softc
structure back under 4 KB.  Alternatively, the receive and transmit
descriptor arrays can be allocated separately, rather then embedded
in the tulip_softc structure.

As long as the tulip_softc structure happens to be mapped to
physically contiguous memory, everything works.  But completely
unrelated kernel changes can cause this to break; symptoms are
that the driver wedges after transmitting about 100 packets.

Jim Shankland