Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753882AbdIDPv2 (ORCPT ); Mon, 4 Sep 2017 11:51:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57954 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753780AbdIDPv1 (ORCPT ); Mon, 4 Sep 2017 11:51:27 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 167A12CE918 Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=jglisse@redhat.com Date: Mon, 4 Sep 2017 11:51:23 -0400 From: Jerome Glisse To: Bob Liu Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, John Hubbard , Dan Williams , David Nellans , Balbir Singh , majiuyue , "xieyisheng (A)" Subject: Re: [HMM-v25 19/19] mm/hmm: add new helper to hotplug CDM memory region v3 Message-ID: <20170904155123.GA3161@redhat.com> References: <20170817000548.32038-1-jglisse@redhat.com> <20170817000548.32038-20-jglisse@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.8.3 (2017-05-23) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Mon, 04 Sep 2017 15:51:27 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1070 Lines: 24 On Mon, Sep 04, 2017 at 11:09:14AM +0800, Bob Liu wrote: > On 2017/8/17 8:05, J?r?me Glisse wrote: > > Unlike unaddressable memory, coherent device memory has a real > > resource associated with it on the system (as CPU can address > > it). Add a new helper to hotplug such memory within the HMM > > framework. > > > > Got an new question, coherent device( e.g CCIX) memory are likely reported to OS > through ACPI and recognized as NUMA memory node. > Then how can their memory be captured and managed by HMM framework? > Only platform that has such memory today is powerpc and it is not reported as regular memory by the firmware hence why they need this helper. I don't think anyone has defined anything yet for x86 and acpi. As this is memory on PCIE like interface then i don't expect it to be reported as NUMA memory node but as io range like any regular PCIE resources. Device driver through capabilities flags would then figure out if the link between the device and CPU is CCIX capable if so it can use this helper to hotplug it as device memory. J?r?me