From owner-freebsd-amd64@FreeBSD.ORG  Sun Nov 30 22:23:39 2003
Return-Path: <owner-freebsd-amd64@FreeBSD.ORG>
Delivered-To: freebsd-amd64@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id C23C416A4CE
	for <freebsd-amd64@freebsd.org>; Sun, 30 Nov 2003 22:23:39 -0800 (PST)
Received: from bigtex.jrv.org (rrcs-sw-24-73-246-106.biz.rr.com
	[24.73.246.106])
	by mx1.FreeBSD.org (Postfix) with ESMTP id B3BE043FAF
	for <freebsd-amd64@freebsd.org>;
	Sun, 30 Nov 2003 22:23:38 -0800 (PST)
	(envelope-from james@bigtex.jrv.org)
Received: from bigtex.jrv.org (localhost [127.0.0.1])
	by bigtex.jrv.org (8.12.1/8.12.1) with ESMTP id hB16Nbo8032875
	(version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO);
	Mon, 1 Dec 2003 00:23:37 -0600 (CST)
Received: (from james@localhost)
	by bigtex.jrv.org (8.12.1/8.12.1/Submit) id hB16Nbbd032872;
	Mon, 1 Dec 2003 00:23:37 -0600 (CST)
Date: Mon, 1 Dec 2003 00:23:37 -0600 (CST)
Message-Id: <200312010623.hB16Nbbd032872@bigtex.jrv.org>
From: James Van Artsdalen <james-freebsd-amd64@jrv.org>
To: freebsd-amd64@freebsd.org
Subject: Re: disk controllers w/ 64-bit addressing?
X-BeenThere: freebsd-amd64@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Porting FreeBSD to the AMD64 platform <freebsd-amd64.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-amd64>,
	<mailto:freebsd-amd64-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-amd64>
List-Post: <mailto:freebsd-amd64@freebsd.org>
List-Help: <mailto:freebsd-amd64-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-amd64>,
	<mailto:freebsd-amd64-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 01 Dec 2003 06:23:39 -0000

I don't think PIO transfers for s/ATA would be as fast as DMA with
bounce-buffers.  Current ATA disk drives can sustain 60 MB/s in the
fast zones.

I'm wondering if anyone else has done the exercise of looking for a
fast disk system for an AMD64 with more than 4 GB of RAM.  I would
prefer to stay with serail-ATA instead of expensive SCSI but I don't
know if any serial-ATA controllers can directly write to memory above
4 GB without a bounce buffer, or if there is a FreeBSD driver for such
a controller.

Date: Sun, 30 Nov 2003 10:31:40 -0500
From: Dave Feustel <dfeustel@mindspring.com>
Subject: Re: disk controllers w/ 64-bit addressing?

64-bit memory addressing for disk transfers can be done in AMD native mode
via programmed i/o. The question is whether 64-bit memory addressing via
dma-controlled memory transfers is possible and/or supported via the disk driver.