From owner-freebsd-hackers Wed Oct 25 22:33:54 1995 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.6.12/8.6.6) id WAA07137 for hackers-outgoing; Wed, 25 Oct 1995 22:33:54 -0700 Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.2.228.19]) by freefall.freebsd.org (8.6.12/8.6.6) with ESMTP id WAA07132 for ; Wed, 25 Oct 1995 22:33:47 -0700 Received: (from bde@localhost) by godzilla.zeta.org.au (8.6.9/8.6.9) id PAA08288; Thu, 26 Oct 1995 15:31:43 +1000 Date: Thu, 26 Oct 1995 15:31:43 +1000 From: Bruce Evans Message-Id: <199510260531.PAA08288@godzilla.zeta.org.au> To: msmith@atrad.adelaide.edu.au, terry@lambert.org Subject: Re: boot disk.... Cc: hackers@FreeBSD.org, lenzi@cwbone.bsi.com.br Sender: owner-hackers@FreeBSD.org Precedence: bulk >Here's a question for any poor sucker with low-level BIOS experience : >If I rewrite the BPT with a new geometry for the disk, can I assume that >subsequent BIOS activity will honour the new geometry? >My guess is no, but it's always worth dreaming 8) No. The (DOS) BPT reflects the BIOS geometry at the time the partition was formatted. If you change the BIOS geometry (which can be changed at least for IDE drives under AMI BIOSes simply by typing the new geometry in the BIOS setup), then the BPT would have to be changed to match. The BPT is one of the few file system tables that (stupidly) depends on the BIOS geometry. If you change just the BPT, then DOS may use the changed geometry, but since it doesn't match the actual (current translated) geometry, it won't work. Bruce