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Hyper-V host emulation of SCSI for virtual DVD device reports SCSI version 0 (UNKNOWN) but is still capable of supporting REPORTLUN. Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11 successfully with virtual DVD ROM device. What happens is that the SCSI scan process falls back to doing sequential probing by INQUIRY. But the storvsc driver has a previous workaround that masks/blocks all errors reports from INQUIRY (or MODE_SENSE) commands. This workaround causes the scan to then populate a full set of bogus LUN's on the target and then sends kernel spinning off into a death spiral doing block reads on the non-existent LUNs. By setting the correct blacklist flags, the target with the DVD device is scanned with REPORTLUN and that works correctly. Patch needs to go in current 4.11, it is safe but not necessary in older kernels. Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com> Reviewed-by: K. Y. Srinivasan <kys@microsoft.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.