From mboxrd@z Thu Jan 1 00:00:00 1970 From: KY Srinivasan Subject: RE: [PATCH 0/2] Hyper-V disk support V3 Date: Wed, 18 Apr 2012 20:21:48 +0000 Message-ID: <426367E2313C2449837CD2DE46E7EAF92CE8E2@CH1PRD0310MB381.namprd03.prod.outlook.com> References: <20120414170223.24f6ea31@pyramind.ukuu.org.uk> <1334575229-7493-1-git-send-email-apw@canonical.com> <20120416122634.7d1357e1@ultron> <20120416182927.GB3346@shadowen.org> <426367E2313C2449837CD2DE46E7EAF92CE0B5@CH1PRD0310MB381.namprd03.prod.outlook.com> <20120418211235.55b9befc@pyramind.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Return-path: Received: from db3ehsobe005.messaging.microsoft.com ([213.199.154.143]:20102 "EHLO db3outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752032Ab2DRUXY convert rfc822-to-8bit (ORCPT ); Wed, 18 Apr 2012 16:23:24 -0400 In-Reply-To: <20120418211235.55b9befc@pyramind.ukuu.org.uk> Content-Language: en-US Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Alan Cox Cc: Andy Whitcroft , Jeff Garzik , "linux-ide@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Mike Sterling > -----Original Message----- > From: Alan Cox [mailto:alan@lxorguk.ukuu.org.uk] > Sent: Wednesday, April 18, 2012 4:13 PM > To: KY Srinivasan > Cc: Andy Whitcroft; Jeff Garzik; linux-ide@vger.kernel.org; linux- > kernel@vger.kernel.org; Mike Sterling > Subject: Re: [PATCH 0/2] Hyper-V disk support V3 > > > The notion of "pass through" in Hyper-V is a little different. IDE devices can be > configured > > under either one of the supported controllers and these devices can either be > virtual disks > > (VHDs) or physical disks. In either case these will be presented to the guest as > IDE devices. > > So what ensures that by skipping it at the ATA device level we will > always find it as a VHD ? If the Hyper-V storage driver is present, then the Hyper-V storage driver will manage the root device (and other devices skipped by the ata driver). So, the check if we are running on Hyper-V is not enough to skip the device in the ata_piix driver; we need to also make sure that the Hyper-V block driver is available to handle the skipped devices. I think the correct approach here is to have a kernel (or an ata_piix module parameter) that can be set to override the skipping of the block device by the ata driver. Distros that are including the Hyper-V storage driver can set this parameter so that when running on Hyper-V, ata can skip the block device. Regards, K. Y > > Alan > >