From owner-freebsd-stable Mon Nov 20 15:29:35 2000 Delivered-To: freebsd-stable@freebsd.org Received: from gndrsh.dnsmgr.net (GndRsh.dnsmgr.net [198.145.92.4]) by hub.freebsd.org (Postfix) with ESMTP id 3283737B4D7; Mon, 20 Nov 2000 15:29:27 -0800 (PST) Received: (from freebsd@localhost) by gndrsh.dnsmgr.net (8.9.3/8.9.3) id PAA19970; Mon, 20 Nov 2000 15:29:19 -0800 (PST) (envelope-from freebsd) From: "Rodney W. Grimes" Message-Id: <200011202329.PAA19970@gndrsh.dnsmgr.net> Subject: Re: Dangerously Dedicated In-Reply-To: from John Baldwin at "Nov 20, 2000 12:56:02 pm" To: jhb@FreeBSD.ORG (John Baldwin) Date: Mon, 20 Nov 2000 15:29:19 -0800 (PST) Cc: roelof@eboa.com, stable@FreeBSD.ORG, Cy.Schubert@uumail.gov.bc.ca, bfoz@glue.umd.edu, imp@village.org X-Mailer: ELM [version 2.4ME+ PL54 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG ... > > Seems people are getting very confused here about what the BIOS cares > > about and what cares about the partition table, what the specs say and > > what software is actually doing what. > > This is true, but incomplete. :( To help deal with the problem of getting the > BIOS to use a geometry that is the same as the one the OS uses to talk to it, > some newer SCSI BIOS's examine the MBR to extract the geometry from that and > then talk in that geometry. In this way, they can conform to any valid MBR, > and you don't have problems with the geometry of the drive and the MBR being > out of sync. Our bogus MBR in boot1 that is used by dangerously > dedicated mode > breaks this though, resulting in machines whose BIOS get a divide by zero > fault > when they try to read from the disk. The divide by zero fault is an actual BIOS implementation bug, and as far as I know Adaptec and Symbios have corrected their code. See other mail. -- Rod Grimes - KD7CAX @ CN85sl - (RWG25) rgrimes@gndrsh.dnsmgr.net To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message