From: KY Srinivasan <kys@microsoft.com>
To: Andy Whitcroft <apw@canonical.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Jeff Garzik <jgarzik@pobox.com>,
"linux-ide@vger.kernel.org" <linux-ide@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Mike Sterling <mike.sterling@microsoft.com>
Subject: RE: [PATCH 0/2] Hyper-V disk support V3
Date: Thu, 19 Apr 2012 13:17:36 +0000 [thread overview]
Message-ID: <426367E2313C2449837CD2DE46E7EAF92CEBF6@CH1PRD0310MB381.namprd03.prod.outlook.com> (raw)
In-Reply-To: <20120419074018.GA3342@shadowen.org>
> -----Original Message-----
> From: Andy Whitcroft [mailto:apw@canonical.com]
> Sent: Thursday, April 19, 2012 3:40 AM
> To: Alan Cox
> Cc: KY Srinivasan; Jeff Garzik; linux-ide@vger.kernel.org; linux-
> kernel@vger.kernel.org; Mike Sterling
> Subject: Re: [PATCH 0/2] Hyper-V disk support V3
>
> On Wed, Apr 18, 2012 at 09:12:35PM +0100, Alan Cox wrote:
> > > 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 ?
>
> My understanding of things is that the if you have disks assigned to the
> guest that they will always appear both on the virtualised SATA contoller
> and on the paravirtualised driver channel. So that assuming a valid
> configuration in which both drivers initialise they will be picked up by
> one or the other.
>
> KY for clarity are we saying the only way a disk can appear in the guest
> is either on the emulated controller or paravirtualised, we will never
> expose real devices into the guest.
You are right. Depending on how the device is configured for the guest, even
in the pass through case, the device will show up as either an emulated device
(if configured under the IDE controllers) or as a device under the synthetic scsi
controller (as seen by the guest). The storvsc driver can handle both these configurations
while the native ata driver can only handle emulated devices. Since, presently we can
only boot off of a device configured under the IDE controller, we have the issue which your
patch addresses.
K. Y
next prev parent reply other threads:[~2012-04-19 13:21 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-29 17:28 [PATCH 1/1] ata_piix: defer disks to the Hyper-V paravirtualised drivers by default Andy Whitcroft
2012-03-30 9:14 ` Victor Miasnikov
2012-03-30 9:14 ` Victor Miasnikov
2012-04-10 16:08 ` KY Srinivasan
2012-04-12 15:55 ` Andy Whitcroft
2012-04-12 20:03 ` Jeff Garzik
2012-04-13 7:37 ` Andy Whitcroft
2012-04-14 15:53 ` [PATCH 0/2] Hyper-V disk support Andy Whitcroft
2012-04-14 15:53 ` [PATCH 1/2] libata: add a host flag to ignore detected ATA devices Andy Whitcroft
2012-04-14 15:53 ` [PATCH 2/2] ata_piix: defer disks to the Hyper-V drivers by default Andy Whitcroft
2012-04-14 16:02 ` Alan Cox
2012-04-15 0:10 ` KY Srinivasan
2012-04-16 11:20 ` [PATCH 0/2] Hyper-V disk support V3 Andy Whitcroft
2012-04-16 11:20 ` [PATCH 1/2] libata: add a host flag to ignore detected ATA devices Andy Whitcroft
2012-04-16 11:20 ` [PATCH 2/2] UBUNTU: SAUCE: ata_piix: defer disks to the Hyper-V drivers by default Andy Whitcroft
2012-04-16 11:28 ` Sergei Shtylyov
2012-04-16 11:26 ` [PATCH 0/2] Hyper-V disk support V3 Alan Cox
2012-04-16 18:29 ` Andy Whitcroft
2012-04-16 18:41 ` KY Srinivasan
2012-04-18 20:12 ` Alan Cox
2012-04-18 20:21 ` KY Srinivasan
2012-04-19 8:15 ` 1) boot flag to disable the Hyper-V IDE drivers: ata_piix.prefer_ms_hyperv=0 2) PIIX_IGNORE_ATA_ON_HYPERV Re: [PATCH 0/2] Hyper-V disk support V3 RE: use hv_storvsc instead of ata_piix to handle the IDE disks devices ( but not for the CD-ROM) Victor Miasnikov
2012-04-19 8:15 ` Victor Miasnikov
2012-04-19 7:40 ` [PATCH 0/2] Hyper-V disk support V3 Andy Whitcroft
2012-04-19 13:17 ` KY Srinivasan [this message]
2012-04-19 14:33 ` [PATCH 0/2] Hyper-V disk support V4 Andy Whitcroft
2012-04-19 14:33 ` [PATCH 1/2] libata: add a host flag to ignore detected ATA devices Andy Whitcroft
2012-04-19 14:33 ` [PATCH 2/2] ata_piix: defer disks to the Hyper-V drivers by default Andy Whitcroft
2012-04-19 15:54 ` Sergei Shtylyov
2012-05-04 21:15 ` [PATCH 0/2] Hyper-V disk support V5 Andy Whitcroft
2012-05-04 21:15 ` [PATCH 1/2] libata: add a host flag to ignore detected ATA devices Andy Whitcroft
2012-05-07 19:43 ` Jeff Garzik
2012-05-04 21:15 ` [PATCH 2/2] ata_piix: defer disks to the Hyper-V drivers by default Andy Whitcroft
2012-04-16 15:32 ` [PATCH 0/2] Hyper-V disk support V3 Jeff Garzik
2012-04-16 18:28 ` Andy Whitcroft
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