Date: Mon, 20 Nov 2000 12:56:02 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> Cc: (Roelof Osinga) <roelof@eboa.com>, stable@FreeBSD.org, (Cy Schubert - ITSD Open Systems Group) <Cy.Schubert@uumail.gov.bc.ca>, (Brandon Fosdick) <bfoz@glue.umd.edu>, (Warner Losh) <imp@village.org> Subject: Re: Dangerously Dedicated Message-ID: <XFMail.001120125602.jhb@FreeBSD.org> In-Reply-To: <200011202023.MAA19454@gndrsh.dnsmgr.net>
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On 20-Nov-00 Rodney W. Grimes wrote: >> In message <3A180EA0.31926227@glue.umd.edu> Brandon Fosdick writes: >> : So we're going to be stuck with MS style partitions on machines that only >> : run >> : FreeBSD? I don't like this idea. >> >> First, these aren't MS style partitions. They are part of the PC >> spec. FreeBSD is lying to the BIOS with the MBR that we put onto the >> disk, and that causes problems. > > 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. -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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