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Petersen" Organization: Oracle Corporation References: <20191105162026.183901-1-maxg@mellanox.com> <20191105162026.183901-2-maxg@mellanox.com> Date: Fri, 08 Nov 2019 20:55:25 -0500 In-Reply-To: (Max Gurtovoy's message of "Thu, 7 Nov 2019 14:02:48 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1.92 (gnu/linux) MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9435 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=887 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1910280000 definitions=main-1911090016 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9435 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=971 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1910280000 definitions=main-1911090016 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191108_175550_028473_84F56EFF X-CRM114-Status: GOOD ( 18.18 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: sagi@grimberg.me, vladimirk@mellanox.com, idanb@mellanox.com, israelr@mellanox.com, linux-nvme@lists.infradead.org, shlomin@mellanox.com, oren@mellanox.com, "Martin K. Petersen" , kbusch@kernel.org, hch@lst.de Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org Max, > So iSER will create a signature resources for every capable device and > connection without giving the user the possibility to distinguish > between needed PI controllers and un-needed PI controllers. > > We don't have a format command in the fabrics so this is the best > option we can think of for adding flexibility to users. > > I spoke with Christoph about the module param possibility and we both > agreed it's not the way to go. > > Let me know if you have an idea that will enable flexibility to users. The way it works in SCSI is that if a user wants to enable PI, they do so when provision the device. So either a format for disk drives or by selecting an option while creating a LUN in a storage array management interface. There are some knobs that can be twiddled on the initiator side to enable/disable PI and/or DIX but these are meant for test or buggy device workaround purposes. Not as a means for the user to select or deselect the feature. The user can decide on a per-device basis whether the block layer should generate PI on write and verify on read. Those are the "proper" policy knobs on the initiator side. When an I/O request is received by the SCSI stack, we inspect it to determine whether we need to allocate one or two scatterlists. If the request has a bip attached, we'll allocate a separate scatterlist which is then used to map the protection information before the I/O is submitted to the device driver. -- Martin K. Petersen Oracle Linux Engineering _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme