From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10136C31E44 for ; Mon, 17 Jun 2019 08:45:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB52020848 for ; Mon, 17 Jun 2019 08:45:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727703AbfFQIpG (ORCPT ); Mon, 17 Jun 2019 04:45:06 -0400 Received: from verein.lst.de ([213.95.11.211]:34464 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725971AbfFQIpG (ORCPT ); Mon, 17 Jun 2019 04:45:06 -0400 Received: by newverein.lst.de (Postfix, from userid 2407) id 6715C68AFE; Mon, 17 Jun 2019 10:44:33 +0200 (CEST) Date: Mon, 17 Jun 2019 10:44:33 +0200 From: Christoph Hellwig To: Kashyap Desai Cc: Christoph Hellwig , Jens Axboe , Sebastian Ott , Sagi Grimberg , Max Gurtovoy , Bart Van Assche , Ulf Hansson , Alan Stern , Oliver Neukum , linux-block@vger.kernel.org, linux-rdma@vger.kernel.org, linux-mmc@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, "PDL,MEGARAIDLINUX" , PDL-MPT-FUSIONLINUX , linux-hyperv@vger.kernel.org, linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH 10/13] megaraid_sas: set virt_boundary_mask in the scsi host Message-ID: <20190617084433.GA7969@lst.de> References: <20190605190836.32354-1-hch@lst.de> <20190605190836.32354-11-hch@lst.de> <20190608081400.GA19573@lst.de> <98f6557ae91a7cdfe8069fcf7d788c88@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <98f6557ae91a7cdfe8069fcf7d788c88@mail.gmail.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Fri, Jun 14, 2019 at 01:28:47AM +0530, Kashyap Desai wrote: > Is there any changes in API blk_queue_virt_boundary? I could not find > relevant code which account for this. Can you help ? > Which git repo shall I use for testing ? That way I can confirm, I didn't > miss relevant changes. Latest mainline plus the series (which is about to get resent). blk_queue_virt_boundary now forced an unlimited max_hw_sectors as that is how PRP-like schemes work, to work around a block driver merging bug. But we also need to communicate that limit to the DMA layer so that we don't set a smaller iommu segment size limitation. > >From your above explanation, it means (after this patch) max segment size > of the MR controller will be set to 4K. > Earlier it is possible to receive single SGE of 64K datalength (Since max > seg size was 64K), but now the same buffer will reach the driver having 16 > SGEs (Each SGE will contain 4K length). No, there is no more limit for the size of the segment at all, as for PRPs each PRP is sort of a segment from the hardware perspective. We just require the segments to not have gaps, as PRPs don't allow for that. That being said I think these patches are wrong for the case of megaraid or mpt having both NVMe and SAS/ATA devices behind a single controller. Is that a valid configuration?