From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: [PATCH] iscsi_iser: Re-enable 'iser_pi_guard' module parameter Date: Wed, 17 Jan 2018 21:04:49 -0500 Message-ID: References: <1515575256-9949-1-git-send-email-hare@suse.de> <20180110230240.GR4518@ziepe.ca> <22838a0f-29d5-7351-12d3-05a0948fd0ba@suse.com> <651bc1dd-f019-637c-1f76-07938b3041ce@grimberg.me> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: (Steven Schremmer's message of "Wed, 17 Jan 2018 20:43:19 +0000") Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Schremmer, Steven" Cc: Sagi Grimberg , "Martin K. Petersen" , Hannes Reinecke , Jason Gunthorpe , Hannes Reinecke , Or Gerlitz , Doug Ledford , "linux-rdma@vger.kernel.org" List-Id: linux-rdma@vger.kernel.org Steven, > If the target uses CRC, the host will need a way to match. AFAIK, > there is no way in the SCSI protocol to determine this, The IP checksum feature is entirely DIX, so no. There is no guard format feature discovery taking place since only the initiator supports IP checksum. It is always T10 CRC on the wire between initiator and target on SAS/FC. > This patch would restore the previous knob which meets the need > for now. If a better method is developed in the future, then great. I'm not against moving the checksum selection up the stack in principle. But it's a lot of churn for little gain, IMHO. So I think I'm in favor of reviving the iser_pi_guard parameter. At least in the short term. -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html