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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 F3E45C47420 for ; Fri, 25 Sep 2020 16:20:14 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 90F6C2076B for ; Fri, 25 Sep 2020 16:20:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 90F6C2076B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 1D3002E176; Fri, 25 Sep 2020 16:20:14 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id SPogTIZq+jMK; Fri, 25 Sep 2020 16:20:13 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id 4A0102045F; Fri, 25 Sep 2020 16:20:13 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 3B69BC0890; Fri, 25 Sep 2020 16:20:13 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 5E0EFC0859 for ; Fri, 25 Sep 2020 16:20:12 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 45C7287585 for ; Fri, 25 Sep 2020 16:20:12 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id qVHhi-n0axLC for ; Fri, 25 Sep 2020 16:20:11 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by hemlock.osuosl.org (Postfix) with ESMTPS id 2303E87581 for ; Fri, 25 Sep 2020 16:20:11 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id B124368BEB; Fri, 25 Sep 2020 18:20:04 +0200 (CEST) Date: Fri, 25 Sep 2020 18:20:03 +0200 From: Christoph Hellwig To: Marek Szyprowski Subject: Re: [PATCH 1/8] dma-mapping: add DMA_ATTR_LOW_ADDRESS attribute Message-ID: <20200925162003.GA18879@lst.de> References: <20200925141218.13550-1-m.szyprowski@samsung.com> <20200925141218.13550-2-m.szyprowski@samsung.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200925141218.13550-2-m.szyprowski@samsung.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: linux-samsung-soc@vger.kernel.org, Bartlomiej Zolnierkiewicz , Sylwester Nawrocki , linux-kernel@vger.kernel.org, Krzysztof Kozlowski , Linux IOMMU , Robin Murphy , Christoph Hellwig , linux-media@vger.kernel.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" > #define DMA_ATTR_PRIVILEGED (1UL << 9) > +/* > + * DMA_ATTR_LOW_ADDRESS: used to indicate that the buffer should be allocated > + * at the lowest possible DMA address, usually just at the beginning of the > + * DMA/IOVA address space ('first-fit' allocation algorithm). > + */ > +#define DMA_ATTR_LOW_ADDRESS (1UL << 10) I think we need better comments explaining that this is best effort and only applies to DMA API implementations that actually have an allocatable IOVA space. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu