From owner-freebsd-arch@FreeBSD.ORG  Wed Jul 28 18:33:59 2004
Return-Path: <owner-freebsd-arch@FreeBSD.ORG>
Delivered-To: freebsd-arch@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 68CF016A4CE
	for <freebsd-arch@freebsd.org>; Wed, 28 Jul 2004 18:33:59 +0000 (GMT)
Received: from imf19aec.mail.bellsouth.net (imf19aec.mail.bellsouth.net
	[205.152.59.67])
	by mx1.FreeBSD.org (Postfix) with ESMTP id CCE2A43D5A
	for <freebsd-arch@freebsd.org>; Wed, 28 Jul 2004 18:33:58 +0000 (GMT)
	(envelope-from sah@coraid.com)
Received: from coraid.com ([68.19.5.244]) by imf19aec.mail.bellsouth.net
          (InterMail vM.5.01.06.08 201-253-122-130-108-20031117) with SMTP
          id <20040728183344.ELWU1792.imf19aec.mail.bellsouth.net@coraid.com>
          for <freebsd-arch@freebsd.org>; Wed, 28 Jul 2004 14:33:44 -0400
Message-Id: <20040728183344.ELWU1792.imf19aec.mail.bellsouth.net@coraid.com>
Date: Wed, 28 Jul 2004 14:33:58 -0400
From: sah@coraid.com
To: undisclosed-recipients: ;
X-Mailman-Approved-At: Thu, 29 Jul 2004 11:58:19 +0000
Subject: AoE & driver tips
X-BeenThere: freebsd-arch@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Discussion related to FreeBSD architecture
	<freebsd-arch.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-arch>
List-Post: <mailto:freebsd-arch@freebsd.org>
List-Help: <mailto:freebsd-arch-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-arch>,
	<mailto:freebsd-arch-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 28 Jul 2004 18:33:59 -0000

Hello,

I'm in the process of writing a AoE disk/protocol driver for freebsd.
AoE (ATA over Ethernet) is used to access ATA devices attached directly to the Ethernet using the AoE registered Ethernet protocol type 0x88a2.  I have already written a driver for linux 2.4 and 2.6 that makes AoE devices show up as local disks.  I'm hoping to do the same for freebsd.  I have some questions from my
initial perusal of the code.

I've been looking at the code in sys/dev/ata/ for tips on plugging into the disk device layer.
It appears that what I want is disk_create && disk_destroy.  How is the parameter "unit" related
to device major & minor?  I don't see anywhere where major and minor are related to the disk
structure, though perhaps I'm just missing it.  Do I need to register a device major?

If a device fails or vanishes, can i just fail the outstanding bios and disk_destroy it?

How does freebsd do SMART on ata?  I'd like to be able to plug into this as well
if the system uses it.

Any other tips/comments about gluing together the disk & network would be appreciated.

Cheers,

Sam
sah@coraid.com