From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.33) id 1ClaUD-0001K7-Ul for qemu-devel@nongnu.org; Mon, 03 Jan 2005 17:15:38 -0500 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.33) id 1ClaUB-0001IQ-UL for qemu-devel@nongnu.org; Mon, 03 Jan 2005 17:15:36 -0500 Received: from [129.104.30.34] (helo=mx1.polytechnique.org) by monty-python.gnu.org with esmtp (Exim 4.34) id 1ClaIo-0002Re-B3 for qemu-devel@nongnu.org; Mon, 03 Jan 2005 17:03:50 -0500 Received: from localhost (localhost [127.0.0.1]) by djali.polytechnique.org (Postfix) with ESMTP id 96292331D4 for ; Mon, 3 Jan 2005 23:03:47 +0100 (CET) Received: from djali.polytechnique.org ([127.0.0.1]) by localhost (localhost [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 16555-02 for ; Mon, 3 Jan 2005 23:03:47 +0100 (CET) Received: from [84.99.204.192] (unknown [84.99.204.192]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ssl.polytechnique.org (Postfix) with ESMTP id 54190331D0 for ; Mon, 3 Jan 2005 23:03:47 +0100 (CET) Message-ID: <41D9C168.8040900@bellard.org> Date: Mon, 03 Jan 2005 23:04:24 +0100 From: Fabrice Bellard MIME-Version: 1.0 Subject: Re: [Qemu-devel] HD Image Size Limits and hdachs References: <41D45541.8010806@brittainweb.org> <20041230223257.GA29967@jbrown.mylinuxbox.org> <41D4880B.1010105@brittainweb.org> In-Reply-To: <41D4880B.1010105@brittainweb.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Hi, Happy new year to all :-) Jason Brittain wrote: > Jim C. Brown wrote: > >> One thing is that the maximum number of heads is 256, not 16. > > > That's a good catch, if true. Thanks. But, the doc (the HTML one from > CVS HEAD) is > very specific about the range being from 1 to 16. I believe you're > probably right > and the doc is wrong. No, the doc is correct. One must distinguish between the Physical CHS (with 16 heads max and this is what -hdachs specifies) and the Logical CHS (with 255 heads max) which is only used by the BIOS to increase the number of sectors that can be addressed. THe logical CHS is specified indirectly when you tell "lba" or "none" as forth argument to -hdachs. Anyway, nowadays CHS is no longer used when accessing modern hard disks, so it is only a problem for old software using the BIOS to access the hard disk. So _never_ use -hdachs, except if you have to use an old DOS disk image coming from another emulator. Fabrice.