From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932458AbeCBWYs (ORCPT ); Fri, 2 Mar 2018 17:24:48 -0500 Received: from ale.deltatee.com ([207.54.116.67]:47022 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932131AbeCBWYq (ORCPT ); Fri, 2 Mar 2018 17:24:46 -0500 To: Benjamin Herrenschmidt , Dan Williams Cc: Jens Axboe , Keith Busch , Oliver OHalloran , Alex Williamson , linux-nvdimm , linux-rdma , linux-pci@vger.kernel.org, Linux Kernel Mailing List , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Jason Gunthorpe , Bjorn Helgaas , Max Gurtovoy , Christoph Hellwig References: <20180228234006.21093-1-logang@deltatee.com> <1519876489.4592.3.camel@kernel.crashing.org> <1519876569.4592.4.camel@au1.ibm.com> <1519936477.4592.23.camel@au1.ibm.com> <2079ba48-5ae5-5b44-cce1-8175712dd395@deltatee.com> <43ba615f-a6e1-9444-65e1-494169cb415d@deltatee.com> <1519945204.4592.45.camel@au1.ibm.com> <595acefb-18fc-e650-e172-bae271263c4c@deltatee.com> <1519946734.4592.48.camel@au1.ibm.com> <1520027052.4592.60.camel@kernel.crashing.org> From: Logan Gunthorpe Message-ID: Date: Fri, 2 Mar 2018 15:24:36 -0700 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: <1520027052.4592.60.camel@kernel.crashing.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: hch@lst.de, maxg@mellanox.com, bhelgaas@google.com, jgg@mellanox.com, jglisse@redhat.com, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-rdma@vger.kernel.org, linux-nvdimm@lists.01.org, alex.williamson@redhat.com, oliveroh@au1.ibm.com, keith.busch@intel.com, axboe@kernel.dk, dan.j.williams@intel.com, benh@kernel.crashing.org X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v2 00/10] Copy Offload in NVMe Fabrics with P2P PCI 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 02/03/18 02:44 PM, Benjamin Herrenschmidt wrote: > Allright, so, I think I have a plan to fix this, but it will take a > little bit of time. > > Basically the idea is to have firmware pass to Linux a region that's > known to not have anything in it that it can use for the vmalloc space > rather than have linux arbitrarily cut the address space in half. > > I'm pretty sure I can always find large enough "holes" in the physical > address space that are outside of both RAM/OpenCAPI/Nvlink and > PCIe/MMIO space. If anything, unused chip IDs. But I don't want Linux > to have to know about the intimate HW details so I'll pass it from FW. > > It will take some time to adjust Linux and get updated FW around > though. > > Once that's done, I'll be able to have the linear mapping go through > the entire 52-bit space (minus that hole). Of course the hole need to > be large enough to hold a vmemmap for a 52-bit space, so that's about > 4TB. So I probably need a hole that's at least 8TB. > > As for the mapping attributes, it should be easy for my linear mapping > code to ensure anything that isn't actual RAM is mapped NC. Very cool. I'm glad to hear you found a way to fix this. Thanks, Logan