From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: [PATCH] storvsc: workaround for virtual DVD SCSI version Date: Tue, 07 Mar 2017 20:21:44 -0500 Message-ID: References: <20170307171553.13247-1-sthemmin@microsoft.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170307171553.13247-1-sthemmin@microsoft.com> (Stephen Hemminger's message of "Tue, 7 Mar 2017 09:15:53 -0800") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" To: Stephen Hemminger Cc: Stephen Hemminger , linux-scsi@vger.kernel.org, martin.petersen@oracle.com, haiyangz@microsoft.com, linux-kernel@vger.kernel.org, hch@lst.de, hare@suse.de, devel@linuxdriverproject.org List-Id: linux-scsi@vger.kernel.org >>>>> "Stephen" == Stephen Hemminger writes: Stephen, Stephen> Hyper-V host emulation of SCSI for virtual DVD device reports Stephen> SCSI version 0 (UNKNOWN) but is still capable of supporting Stephen> REPORTLUN. Stephen> Without this patch, a GEN2 Linux guest on Hyper-V will not boot Stephen> 4.11 successfully with virtual DVD ROM device. What happens is Stephen> that the SCSI scan process falls back to doing sequential Stephen> probing by INQUIRY. But the storvsc driver has a previous Stephen> workaround that masks/blocks all errors reports from INQUIRY Stephen> (or MODE_SENSE) commands. This workaround causes the scan to Stephen> then populate a full set of bogus LUN's on the target and then Stephen> sends kernel spinning off into a death spiral doing block reads Stephen> on the non-existent LUNs. Stephen> By setting the correct blacklist flags, the target with the DVD Stephen> device is scanned with REPORTLUN and that works correctly. Applied to 4.11/scsi-fixes. Thank you! -- Martin K. Petersen Oracle Linux Engineering