From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3223C04EBF for ; Wed, 5 Dec 2018 14:43:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 867C720878 for ; Wed, 5 Dec 2018 14:43:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="TT23gtRI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 867C720878 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727867AbeLEOnW (ORCPT ); Wed, 5 Dec 2018 09:43:22 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:43926 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727135AbeLEOnV (ORCPT ); Wed, 5 Dec 2018 09:43:21 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=/L0uBM6DoEflxkum1yP/GbMdESPWeER5F10xyxcKreE=; b=TT23gtRIDM/FtcG+a3giH+J+5 JG+ALJ65QPQP0f3m9DbidDMZEWP2+0O9X1NLlas14Q+xwH3GM3a+zB4z51S5fmt5Yb++akyAzY4Yt zMIfad2FyvjRLH60vWTo9RXu8JCCpR2en8E65hbIIgX+sxD1p0zaqMcIPfFmtksWW1vFtF6rg1vHr M6YtQZR/8W7zXrUuCBoHUKxOFNx5P8mM0vUzFVjD8cxxfnQ8atVXWI/jLhhS0CR0/WvRF2RP5dsQs cWzpHPN8pedYPm70jz4JOKH/WWaM3ws+I2msquVc2flVrdBjz4ipVzJ1VftgPNf4JVdHizCUt7U0t 6sep9Xy+g==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gUYOK-0007gE-O2; Wed, 05 Dec 2018 14:43:08 +0000 Date: Wed, 5 Dec 2018 06:43:08 -0800 From: Christoph Hellwig To: Robin Murphy Cc: Christoph Hellwig , Nicolas Boichat , Will Deacon , Joerg Roedel , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Michal Hocko , Mel Gorman , Levin Alexander , Huaisheng Ye , Mike Rapoport , linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Yong Wu , Matthias Brugger , Tomasz Figa , yingjoe.chen@mediatek.com, Matthew Wilcox Subject: Re: [PATCH v4 3/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging Message-ID: <20181205144308.GA28409@infradead.org> References: <20181205054828.183476-1-drinkcat@chromium.org> <20181205054828.183476-4-drinkcat@chromium.org> <20181205135406.GA29031@infradead.org> <1d211576-9153-cca1-5cd0-8c9881bd3fa4@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1d211576-9153-cca1-5cd0-8c9881bd3fa4@arm.com> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 05, 2018 at 02:40:06PM +0000, Robin Murphy wrote: > 32-bit Arm doesn't have ZONE_DMA32, but has (or at least had at the time) a > 2GB ZONE_DMA. Whether we actually need that or not depends on how this all > interacts with LPAE and highmem, but I'm not sure of those details off-hand. Well, arm32 can't address more than 32-bits in the linear kernel mapping, so GFP_KERNEL should be perfectly fine there if the limit really is 32-bits and not 31 or smaller because someone stole a bit or two somewhere.