Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753016AbcKUCJG (ORCPT ); Sun, 20 Nov 2016 21:09:06 -0500 Received: from mail-pg0-f65.google.com ([74.125.83.65]:32858 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752203AbcKUCJC (ORCPT ); Sun, 20 Nov 2016 21:09:02 -0500 Subject: Re: [HMM v13 07/18] mm/ZONE_DEVICE/x86: add support for un-addressable device memory To: =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <1479493107-982-1-git-send-email-jglisse@redhat.com> <1479493107-982-8-git-send-email-jglisse@redhat.com> Cc: John Hubbard , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" From: Balbir Singh Message-ID: <33e9c941-ac57-3dfd-2ed9-c1d058a57d8f@gmail.com> Date: Mon, 21 Nov 2016 13:08:56 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.0 MIME-Version: 1.0 In-Reply-To: <1479493107-982-8-git-send-email-jglisse@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 551 Lines: 16 On 19/11/16 05:18, Jérôme Glisse wrote: > It does not need much, just skip populating kernel linear mapping > for range of un-addressable device memory (it is pick so that there > is no physical memory resource overlapping it). All the logic is in > share mm code. > > Only support x86-64 as this feature doesn't make much sense with > constrained virtual address space of 32bits architecture. > Is there a reason this would not work on powerpc64 for example? Could you document the limitations -- testing/APIs/missing features? Balbir Singh.