Received: by 2002:a05:6a10:a0d1:0:0:0:0 with SMTP id j17csp2897731pxa; Tue, 25 Aug 2020 06:27:28 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxgmRoRa8WGzrft3B1G17l2Ol8ghd7ODomRleDIZiXYIt9Mx2PUgGTqoZuqPsMqlozR70oK X-Received: by 2002:a17:906:d187:: with SMTP id c7mr10889181ejz.196.1598362048160; Tue, 25 Aug 2020 06:27:28 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1598362048; cv=none; d=google.com; s=arc-20160816; b=E2le3yVCqz68qd3mwpWK7wqpCembj4dnbJo25zlp3RgOE67tJcD+fbrW+4898qg9L2 XNjcMpASa67nX+aehpt/w6ufpv9SjqgFziRK95JF9cZibHRQ/uw94il89OQy+u1l7oAL uFaMasKbhc4jKj/e3ZJVSqQKiznVIHAmzJSwBUubf8H7yJPEg7tXwa99K6MX5LPRTF2U vXMzoBNfEc9/6BqZMmLvr7fWrwGLMXYEFlcXP62LqFP3gDrw+4Pi6GXXBIMd+KrjfYc1 q8p4BmLN+TJCN9Pzi0CO6m4Oho+FUYv8M3mL0A5crd3Yh/NOYB8V8/vbyVHzv+fmmmKr BWSQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:user-agent:in-reply-to :content-disposition:mime-version:references:message-id:subject:cc :to:from:date; bh=Me+CjYbdBrU+6GjRMisT0s/vBQ8NW56Nv7ZGIamUnvE=; b=zRTcWOWc8lkGgQ/pYqBN4ncS42Cu+eA30gJa1NpsC4xw9KyNIFRyn9aXJcKldkiLP6 YzM+5yjW+5mogN8pD7ho14dXyUsO9vF27wxdiJZtXCKSW5rqYfrQi5ffol4FOkDW9uT1 XyYJTeqSVZv0NYf+M5chboJiylUYwmT/eH9PXJx4tjsz+JtM7D3xhvvGayWmsdM0oyg7 pWKyKVRpyYRKVm2bayp+TBqsFCoVvmMxnd8JOYfWs0cukWFRVCuHISjEYSR0wpXwjNiW ZKMdnb6iHlu9s4sgmKg2JRBXFupYtzaDxRQt6lVt1JZzf6YRNFtyUb9/b6DeFSV70Jdt IBwA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id v26si1228622edb.179.2020.08.25.06.27.04; Tue, 25 Aug 2020 06:27:28 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726580AbgHYN0V (ORCPT + 99 others); Tue, 25 Aug 2020 09:26:21 -0400 Received: from verein.lst.de ([213.95.11.211]:58839 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726149AbgHYN0S (ORCPT ); Tue, 25 Aug 2020 09:26:18 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 6E33E68BEB; Tue, 25 Aug 2020 15:26:12 +0200 (CEST) Date: Tue, 25 Aug 2020 15:26:12 +0200 From: Christoph Hellwig To: Marek Szyprowski Cc: Christoph Hellwig , Mauro Carvalho Chehab , Thomas Bogendoerfer , "James E.J. Bottomley" , Joonyoung Shim , Seung-Woo Kim , Kyungmin Park , Ben Skeggs , Pawel Osciak , Matt Porter , iommu@lists.linux-foundation.org, Tom Lendacky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-samsung-soc@vger.kernel.org, nouveau@lists.freedesktop.org, netdev@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, linux-mm@kvack.org, alsa-devel@alsa-project.org Subject: Re: a saner API for allocating DMA addressable pages Message-ID: <20200825132612.GA22318@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <8fa1ce36-c783-1a02-6890-211eb504a33b@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8fa1ce36-c783-1a02-6890-211eb504a33b@samsung.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 25, 2020 at 01:30:41PM +0200, Marek Szyprowski wrote: > I really wonder what is the difference between this new API and > alloc_pages(GFP_DMA, n). Is this API really needed? I thought that this > is legacy thing to be removed one day... The difference is that the pages returned are guranteed to be addressable by the devie. This is a very important difference that matters for a lot of use cases.