From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7490DC31E46 for ; Wed, 12 Jun 2019 13:09:30 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4DA6120874 for ; Wed, 12 Jun 2019 13:09:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4DA6120874 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:60200 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hb30L-0000q5-Ej for qemu-devel@archiver.kernel.org; Wed, 12 Jun 2019 09:09:29 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60215) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hb2ya-0007tu-FP for qemu-devel@nongnu.org; Wed, 12 Jun 2019 09:07:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hb2yZ-00015Q-D9 for qemu-devel@nongnu.org; Wed, 12 Jun 2019 09:07:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39176) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hb2yP-0000iL-6B; Wed, 12 Jun 2019 09:07:31 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A3AF959473; Wed, 12 Jun 2019 13:06:51 +0000 (UTC) Received: from sirius.home.kraxel.org (ovpn-117-25.ams2.redhat.com [10.36.117.25]) by smtp.corp.redhat.com (Postfix) with ESMTP id 435D51001B0A; Wed, 12 Jun 2019 13:06:51 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 1243C16E08; Wed, 12 Jun 2019 15:06:50 +0200 (CEST) Date: Wed, 12 Jun 2019 15:06:50 +0200 From: Gerd Hoffmann To: Sam Eiderman Message-ID: <20190612130650.xftda65kgnsefyvs@sirius.home.kraxel.org> References: <20190612115939.23825-1-shmuel.eiderman@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190612115939.23825-1-shmuel.eiderman@oracle.com> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Wed, 12 Jun 2019 13:06:56 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [QEMU] [PATCH v2 0/8] Add Qemu to SeaBIOS LCHS interface X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-block@nongnu.org, arbel.moshe@oracle.com, seabios@seabios.org, qemu-devel@nongnu.org, mreitz@redhat.com, kevin@koconnor.net, liran.alon@oracle.com, karl.heubaum@oracle.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jun 12, 2019 at 02:59:31PM +0300, Sam Eiderman wrote: > v1: > > Non-standard logical geometries break under QEMU. > > A virtual disk which contains an operating system which depends on > logical geometries (consistent values being reported from BIOS INT13 > AH=08) will most likely break under QEMU/SeaBIOS if it has non-standard > logical geometries - for example 56 SPT (sectors per track). > No matter what QEMU will guess - SeaBIOS, for large enough disks - will > use LBA translation, which will report 63 SPT instead. --verbose please. As far I know seabios switches to LBA mode when the disk is simply too big for LCHS addressing. So I fail to see which problem is solved by this. If your guest needs LCHS, why do you assign a disk which can't be fully accessed using LCHS addressing? > In addition we can not enforce SeaBIOS to rely on phyiscal geometries at > all. A virtio-blk-pci virtual disk with 255 phyiscal heads can not > report more than 16 physical heads when moved to an IDE controller, the > ATA spec allows a maximum of 16 heads - this is an artifact of > virtualization. Well, not really. Moving disks from one controller to another when the OS depends on LHCS addressing never is a good idea. That already caused problems in the 90-ies, when moving scsi disks from one scsi host adapter to another type, *way* before virtualization became a thing. BTW: One possible way to figure which LCHS layout a disk uses is to check the MBR partition table. With that we (a) don't need a new interface between qemu and seabios and (b) it is not needed to manually specify the geometry. cheers, Gerd