From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752236AbeCZPnw (ORCPT ); Mon, 26 Mar 2018 11:43:52 -0400 Received: from ale.deltatee.com ([207.54.116.67]:58632 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751840AbeCZPnt (ORCPT ); Mon, 26 Mar 2018 11:43:49 -0400 To: Stephen Bates , Bjorn Helgaas Cc: Sinan Kaya , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "linux-rdma@vger.kernel.org" , "linux-nvdimm@lists.01.org" , "linux-block@vger.kernel.org" , Christoph Hellwig , Jens Axboe , Keith Busch , Sagi Grimberg , Bjorn Helgaas , Jason Gunthorpe , Max Gurtovoy , Dan Williams , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Benjamin Herrenschmidt , Alex Williamson References: <3ea80992-a0fc-08f2-d93d-ae0ec4e3f4ce@codeaurora.org> <4eb6850c-df1b-fd44-3ee0-d43a50270b53@deltatee.com> <757fca36-dee4-e070-669e-f2788bd78e41@codeaurora.org> <4f761f55-4e9a-dccb-d12f-c59d2cd689db@deltatee.com> <20180313230850.GA45763@bhelgaas-glaptop.roam.corp.google.com> <20180323215046.GC210003@bhelgaas-glaptop.roam.corp.google.com> <20180324034947.GE210003@bhelgaas-glaptop.roam.corp.google.com> <121026DC-40C7-4F4E-BE27-BDA652BDEB6A@raithlin.com> From: Logan Gunthorpe Message-ID: <3a25744b-daa1-84e3-fbdc-5db2e81d0540@deltatee.com> Date: Mon, 26 Mar 2018 09:43:17 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <121026DC-40C7-4F4E-BE27-BDA652BDEB6A@raithlin.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: alex.williamson@redhat.com, benh@kernel.crashing.org, jglisse@redhat.com, dan.j.williams@intel.com, maxg@mellanox.com, jgg@mellanox.com, bhelgaas@google.com, sagi@grimberg.me, keith.busch@intel.com, axboe@kernel.dk, hch@lst.de, linux-block@vger.kernel.org, linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, okaya@codeaurora.org, helgaas@kernel.org, sbates@raithlin.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v3 01/11] PCI/P2PDMA: Support peer-to-peer memory X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/03/18 09:28 AM, Stephen Bates wrote: > 1. There is no requirement for a single function to support internal DMAs but in the case of NVMe we do have a protocol specific way for a NVMe function to indicate it supports via the CMB BAR. Other protocols may also have such methods but I am not aware of them at this time. > > 2. For multi-function end-points I think it is a requirement that DMAs *between* functions are supported via an internal path but this can be over-ridden by ACS when supported in the EP. > > 3. For multi-function end-points there is no requirement to support internal DMA within each individual function (i.e. a la point 1 but extended to each function in a MF device). Yeah, that make sense. I wasn't making a huge distinction between single and multi-function devices because from an implementation point of view it's not that different. Logan