From owner-cvs-all Thu Oct 24 17: 1:57 2002 Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BC26C37B401; Thu, 24 Oct 2002 17:01:55 -0700 (PDT) Received: from harmony.village.org (rover.bsdimp.com [204.144.255.66]) by mx1.FreeBSD.org (Postfix) with ESMTP id E9C8F43E6E; Thu, 24 Oct 2002 17:01:54 -0700 (PDT) (envelope-from imp@bsdimp.com) Received: from localhost (warner@rover2.village.org [10.0.0.1]) by harmony.village.org (8.12.3/8.12.3) with ESMTP id g9P01qpk000968; Thu, 24 Oct 2002 18:01:53 -0600 (MDT) (envelope-from imp@bsdimp.com) Date: Thu, 24 Oct 2002 18:00:30 -0600 (MDT) Message-Id: <20021024.180030.103860565.imp@bsdimp.com> To: mark@thuvia.demon.co.uk Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/lib/libdisk Makefile chunk.c write_alpha_dis From: "M. Warner Losh" In-Reply-To: <200210241956.g9OJuQ43046607@dotar.thuvia.org> References: <200210241956.g9OJuQ43046607@dotar.thuvia.org> X-Mailer: Mew version 2.1 on Emacs 21.2 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG In message: <200210241956.g9OJuQ43046607@dotar.thuvia.org> Mark Valentine writes: : > From: John Baldwin : > Date: Thu 24 Oct, 2002 : > Subject: Re: cvs commit: src/lib/libdisk Makefile chunk.c write_alpha_dis : : > How about Adaptec SCSI BIOS's and other "smart" BIOS's that look : > at the MBR to guess what geometry you are using so that they can : > adjust their BIOS to DTRT? These choke if you don't have a valid : > MBR. MBR's are part of the i386 defacto architecture, deal. : : Don't these BIOSs have fallbacks for the case where there's no DOS-style : MBR partition table? The PC BIOS copes with it for IDE disks using the : disk type stuff or whatever; it should be no different for a SCSI BIOS. should be != reality. I have some aha scsi controllers that seem to get really cranky when you don't have an MBR on the disk and the BIOS is enabled for them. : As I said, if that's broken and you *really* need the MBR partitioning : table as a crutch, it's important not to force that to affect the user- : visible partition labelling scheme for the common case of one BSD disklabel : per disk. On the pc architecture you are requires to have a MBR. This is a non-optional part of the 'de-facto' spec. All FreeBSD labeled disks have a MBR on them, even the DD ones. With DD mode, the MBR is bogus in that it doesn't describe the actual hardware. We've been through this about a dozen times now in various forums. The problem here is one of historical usage. /dev/ad0a has worked on FreeBSD since 0.0 and back into the 4.[34] BSD past before that. Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message