Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752480AbcLFWCZ (ORCPT ); Tue, 6 Dec 2016 17:02:25 -0500 Received: from mail-oi0-f54.google.com ([209.85.218.54]:35020 "EHLO mail-oi0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751567AbcLFWCW (ORCPT ); Tue, 6 Dec 2016 17:02:22 -0500 MIME-Version: 1.0 In-Reply-To: References: <61a2fb07344aacd81111449d222de66e.squirrel@webmail.raithlin.com> <20161205171830.GB27784@obsidianresearch.com> <20161205180231.GA28133@obsidianresearch.com> <20161206163850.GC28066@obsidianresearch.com> <20161206172838.GB19318@obsidianresearch.com> From: Dan Williams Date: Tue, 6 Dec 2016 14:02:19 -0800 Message-ID: Subject: Re: Enabling peer to peer device transactions for PCIe devices To: Logan Gunthorpe Cc: Jason Gunthorpe , Stephen Bates , Haggai Eran , "linux-kernel@vger.kernel.org" , "linux-rdma@vger.kernel.org" , "linux-nvdimm@ml01.01.org" , "christian.koenig@amd.com" , "Suravee.Suthikulpanit@amd.com" , "John.Bridgman@amd.com" , "Alexander.Deucher@amd.com" , "Linux-media@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , Max Gurtovoy , "linux-pci@vger.kernel.org" , "serguei.sagalovitch@amd.com" , "Paul.Blinzer@amd.com" , "Felix.Kuehling@amd.com" , "ben.sander@amd.com" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 523 Lines: 12 On Tue, Dec 6, 2016 at 1:47 PM, Logan Gunthorpe wrote: > Hey, > >> Okay, so clearly this needs a kernel side NVMe specific allocator >> and locking so users don't step on each other.. > > Yup, ideally. That's why device dax isn't ideal for this application: it > doesn't provide any way to prevent users from stepping on each other. On this particular point I'm in the process of posting patches that allow device-dax sub-division, so you could carve up a bar into multiple devices of various sizes.