From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with archive (Exim 4.43) id 1Q0b7i-00071T-4N for mharc-grub-devel@gnu.org; Fri, 18 Mar 2011 10:57:54 -0400 Received: from [140.186.70.92] (port=33969 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Q0b7d-0005qP-Aq for grub-devel@gnu.org; Fri, 18 Mar 2011 10:57:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Q0b6N-0002qq-Vf for grub-devel@gnu.org; Fri, 18 Mar 2011 10:56:32 -0400 Received: from mail-bw0-f41.google.com ([209.85.214.41]:38430) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Q0b6N-0002qQ-OH for grub-devel@gnu.org; Fri, 18 Mar 2011 10:56:31 -0400 Received: by bwz17 with SMTP id 17so3829137bwz.0 for ; Fri, 18 Mar 2011 07:56:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:message-id:date:from:user-agent:mime-version:to :subject:references:in-reply-to:content-type :content-transfer-encoding; bh=BNbYx+Rvbz3/0xtwflj6ZjFP5nuwGB+hgbvDVh9Nn9c=; b=E71y0wMRbwxQa9aekyyyzyfLS2Xgll1fZQyLnoPDgEYUajDZpUZD9qXL1urg6tq3ia 6yb9JAQuJ/3Hv28oDag9n3eo0BiGrva1K36Sz4CF4H8ct2xeqruuutXGursjPFYQw+E2 En/jmm5mminUREZOuDlBgAQzZzmlk23dVPRM0= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:subject:references :in-reply-to:content-type:content-transfer-encoding; b=Kl1JPpbC1fj362HbkyqbXsh4nHtW40zvC5Fn5vqH0k1mDxTpYaDgGAE7BlcPmqWCPJ OO8garj9/m3lM36qaisIC+LkOPpV4vQLQqnnO7gadvp1wU1e5R3V4RUkTEH6AVaXGsQA /VcdRE7wFM0IH+TxNY6lndo0L0WrkBuh0Z/QM= Received: by 10.204.81.27 with SMTP id v27mr1042844bkk.115.1300460190531; Fri, 18 Mar 2011 07:56:30 -0700 (PDT) Received: from [147.210.129.245] (laptop-147-210-129-245.labri.fr [147.210.129.245]) by mx.google.com with ESMTPS id c11sm2207098bkc.2.2011.03.18.07.56.28 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 18 Mar 2011 07:56:29 -0700 (PDT) Message-ID: <4D83729B.9060504@gmail.com> Date: Fri, 18 Mar 2011 15:56:27 +0100 From: =?UTF-8?B?R3LDqWdvaXJlIFN1dHJl?= User-Agent: Mozilla/5.0 (X11; U; NetBSD i386; en-US; rv:1.9.2.13) Gecko/20110128 Lightning/1.0b3pre Lanikai/3.1.7 MIME-Version: 1.0 To: The development of GNU GRUB References: <20110316151332.GC343@caffeine.csclub.uwaterloo.ca> <4D80D75C.9080007@gmail.com> <20110316173216.GE343@caffeine.csclub.uwaterloo.ca> <4D810D54.1020008@cfl.rr.com> <4D83202A.9060900@gmail.com> <20110318142253.GO343@caffeine.csclub.uwaterloo.ca> In-Reply-To: <20110318142253.GO343@caffeine.csclub.uwaterloo.ca> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 2) X-Received-From: 209.85.214.41 Subject: Re: How to debug 'out of disk' error. X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: The development of GNU GRUB List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 18 Mar 2011 14:57:52 -0000 On 03/18/2011 15:22, Lennart Sorensen wrote: > On Fri, Mar 18, 2011 at 10:04:42AM +0100, Grégoire Sutre wrote: >> I didn't look at the code, but this is probably the ATA geometry of >> the disk, which is returned by the INT-13h (Extended) function 48h >> (Read Drive Parameters). If I remember correctly, this geometry is >> always 16383/16/63 for disks larger than 8.4GB. > > That does match what is returned. > > Grub later assumes H=255 if it falls back to CHS as far as I can tell. If the standard (non-extended) INT-13h interface is used, then addressing is performed via CHS, and w.r.t. to the BIOS geometry (which need not be the same as the ATA geometry reported by the disk itself, due to potential address translation by the BIOS). I guess that H=255 is the from the BIOS geometry of the disk (as returned by the INT-13h function 08h). > H=255 S=63 would be really bad for alignment on SSDs and such (not that > H=16 is a whole lot better, but it is better). The geometry just says how to interpret CHS addresses, it does not imply any partition alignment. You can have 1MiB-aligned partitions even with a n/255/63 BIOS geometry. Grégoire