From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751776AbeCZUma (ORCPT ); Mon, 26 Mar 2018 16:42:30 -0400 Received: from ale.deltatee.com ([207.54.116.67]:56632 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750983AbeCZUm2 (ORCPT ); Mon, 26 Mar 2018 16:42:28 -0400 To: Jason Gunthorpe Cc: Jonathan Cameron , 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, Stephen Bates , Christoph Hellwig , Jens Axboe , Keith Busch , Sagi Grimberg , Bjorn Helgaas , Max Gurtovoy , Dan Williams , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Benjamin Herrenschmidt , Alex Williamson , Eric Wehage References: <20180312193525.2855-1-logang@deltatee.com> <20180312193525.2855-2-logang@deltatee.com> <59fd2f5d-177f-334a-a9c4-0f8a6ec7c303@codeaurora.org> <24d8e5c2-065d-8bde-3f5d-7f158be9c578@deltatee.com> <20180326121138.00005e30@huawei.com> <20180326164129.GF15530@mellanox.com> <6ead7f19-c0e5-5584-2518-1e1889a007e4@deltatee.com> <20180326193502.GI15530@mellanox.com> From: Logan Gunthorpe Message-ID: <45fcaa2d-214c-f0a9-94d4-b26692b9a5f3@deltatee.com> Date: Mon, 26 Mar 2018 14:42:05 -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: <20180326193502.GI15530@mellanox.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: Eric.Wehage@huawei.com, alex.williamson@redhat.com, benh@kernel.crashing.org, jglisse@redhat.com, dan.j.williams@intel.com, maxg@mellanox.com, bhelgaas@google.com, sagi@grimberg.me, keith.busch@intel.com, axboe@kernel.dk, hch@lst.de, sbates@raithlin.com, 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, Jonathan.Cameron@huawei.com, jgg@mellanox.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 26/03/18 01:35 PM, Jason Gunthorpe wrote: > I think this is another case of the HW can do it but the SW support is > missing. IOMMU configuration and maybe firmware too, for instance. Nope, not sure how you can make this leap. We've been specifically told that peer-to-peer PCIe DMA is not supported on P9. We've also been told there is a very limited (ie. store only), low performance mode designed for poking mailboxes but it is disabled by default and must be enable with some kind of special firmware calls. Logan