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From devnull@lkml.org Tue May 14 22:58:31 2024 Delivery-date: Fri, 17 Feb 2006 21:05:13 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751589AbWBQUEm (ORCPT ); Fri, 17 Feb 2006 15:04:42 -0500 Received: from odyssey.analogic.com ([204.178.40.5]:31503 "EHLO odyssey.analogic.com") by vger.kernel.org with ESMTP id S1751585AbWBQUEl convert rfc822-to-8bit (ORCPT ); Fri, 17 Feb 2006 15:04:41 -0500 Received: from chaos.analogic.com ([10.112.50.11]) by phoenix.analogic.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 17 Feb 2006 15:04:38 -0500 Received: from chaos.analogic.com (localhost [127.0.0.1]) by chaos.analogic.com (8.12.11/8.12.11) with ESMTP id k1HK4cUM004340; Fri, 17 Feb 2006 15:04:38 -0500 Mime-Version: 1.0 Received: (from linux-os@localhost) by chaos.analogic.com (8.12.11/8.12.11/Submit) id k1HK4cgq004339; Fri, 17 Feb 2006 15:04:38 -0500 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT In-Reply-To: <43F617FA.2030609@wolfmountaingroup.com> X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 X-OriginalArrivalTime: 17 Feb 2006 20:04:38.0511 (UTC) FILETIME=[61AD07F0:01C633FD] content-class: urn:content-classes:message Subject: Re: C/H/S from user space Date: Fri, 17 Feb 2006 15:04:38 -0500 Message-Id: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: C/H/S from user space Thread-Index: AcYz/WG0m1CYRNPpQB6/32/HGsEiVg== References: <43F617FA.2030609@wolfmountaingroup.com> From: "linux-os \(Dick Johnson\)" To: "Jeff V. Merkey" Cc: "Linux kernel" Reply-To: "linux-os \(Dick Johnson\)" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 17 Feb 2006, Jeff V. Merkey wrote: > > Dick, > > The model Netware uses for large drives for calculating C/H/S addressed > this problem years ago and > provides more useful output, since C/H/S is converted into a hieristic > which acts almost like an MD5 hash > and for a given dimension, does provide unique output for even very > large drives. > > Code Attached. > > Jeff > > > > ULONG SetPartitionTableGeometry(BYTE *hd, BYTE *sec, BYTE *cyl, > ULONG LBA, ULONG TracksPerCylinder, > ULONG SectorsPerTrack) > { > ULONG offset, cylinders, head, sector; > > if (!cyl || !hd || !sec) > return -1; > > cylinders = (LBA / (TracksPerCylinder * SectorsPerTrack)); > offset = LBA % (TracksPerCylinder * SectorsPerTrack); > head = (WORD)(offset / SectorsPerTrack); > sector = (WORD)(offset % SectorsPerTrack) + 1; > > if (cylinders < 1023) > { > *sec = (BYTE)sector; > *hd = (BYTE)head; > *cyl = (BYTE)(cylinders & 0xff); > *sec |= (BYTE)((cylinders >> 2) & 0xC0); > } > else > { > *sec = (BYTE)(SectorsPerTrack | 0xC0); > *hd = (BYTE)(TracksPerCylinder - 1); > *cyl = (BYTE)0xFE; > } > > return 0; > } > > ULONG SetPartitionTableValues(struct PartitionTableEntry *Part, > ULONG Type, > ULONG StartingLBA, > ULONG EndingLBA, > ULONG Flag, > ULONG TracksPerCylinder, > ULONG SectorsPerTrack) > { > > Part->SysFlag = (BYTE) Type; > Part->fBootable = (BYTE) Flag; > Part->StartLBA = StartingLBA; > Part->nSectorsTotal = (EndingLBA - StartingLBA) + 1; > > SetPartitionTableGeometry(&Part->HeadStart, &Part->SecStart, > &Part->CylStart, > StartingLBA, TracksPerCylinder, SectorsPerTrack); > > SetPartitionTableGeometry(&Part->HeadEnd, &Part->SecEnd, &Part->CylEnd, > EndingLBA, TracksPerCylinder, SectorsPerTrack); > > return 0; > > } > > > [SNIPPED...] Yes, it's a very good model, in fact what I've been talking about. However, several people who refused to read or understand, insisted upon obtaining the exact same C/H/S that the machine claimed to use when it was booted. So, since Linux doesn't destroy that information remaining in the BIOS tables, I show how to make it available to a 'root' user. Observation over several machines will show that the BIOS always uses the same stuff for large media and, in fact, it has no choice. Basically, this means that the first part of the boot-code, the stuff that needs to be translated to fit into the int 0x13 registers, needs to be below 1024 cylinders, 63 sectors-track, and 256 heads. Trivial... even LILO was able to do that! Once the machine boots past the requirement to use the BIOS services, it's a CHS=NOP. Cheers, Dick Johnson Penguin : Linux version 2.6.15.4 on an i686 machine (5589.53 BogoMips). 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