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=-5.2 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 58E17C433E0 for ; Tue, 9 Feb 2021 09:36:58 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 A2E7C64E75 for ; Tue, 9 Feb 2021 09:36:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A2E7C64E75 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 hemlock.osuosl.org (Postfix) with ESMTP id 66392872E6; Tue, 9 Feb 2021 09:36:57 +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 l1jMSmTO9nhm; Tue, 9 Feb 2021 09:36:53 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by hemlock.osuosl.org (Postfix) with ESMTP id 578F586190; Tue, 9 Feb 2021 09:36:53 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 298A7C0891; Tue, 9 Feb 2021 09:36:53 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id A7CB9C013A for ; Tue, 9 Feb 2021 09:36:51 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 91B5A847F8 for ; Tue, 9 Feb 2021 09:36:51 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id VyfYBOuPruYh for ; Tue, 9 Feb 2021 09:36:46 +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 fraxinus.osuosl.org (Postfix) with ESMTPS id 1691884771 for ; Tue, 9 Feb 2021 09:36:46 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 3634268B02; Tue, 9 Feb 2021 10:36:42 +0100 (CET) Date: Tue, 9 Feb 2021 10:36:42 +0100 From: Christoph Hellwig To: Greg KH Subject: Re: DMA direct mapping fix for 5.4 and earlier stable branches Message-ID: <20210209093642.GA1006@lst.de> References: <27bbe35deacb4ca49f31307f4ed551b5@SOC-EX02V.e01.socionext.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: sumit.garg@linaro.org, daniel.thompson@linaro.org, obayashi.yoshimasa@socionext.com, stable@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, robin.murphy@arm.com, hch@lst.de 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" On Tue, Feb 09, 2021 at 10:23:12AM +0100, Greg KH wrote: > > From the view point of ZeroCopy using DMABUF, is 5.4 not > > mature enough, and is 5.10 enough mature ? > > This is the most important point for judging migration. > > How do you judge "mature"? > > And again, if a feature isn't present in a specific kernel version, why > would you think that it would be a viable solution for you to use? I'm pretty sure dma_get_sgtable has been around much longer and was supposed to work, but only really did work properly for arm32, and for platforms with coherent DMA. I bet he is using non-coherent arm64, and it would be broken for other drivers there as well if people did test them, which they apparently so far did not. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu 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, 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 66D78C433DB for ; Tue, 9 Feb 2021 09:42:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 30A2164E88 for ; Tue, 9 Feb 2021 09:42:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229916AbhBIJlr (ORCPT ); Tue, 9 Feb 2021 04:41:47 -0500 Received: from verein.lst.de ([213.95.11.211]:45736 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230264AbhBIJhZ (ORCPT ); Tue, 9 Feb 2021 04:37:25 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 3634268B02; Tue, 9 Feb 2021 10:36:42 +0100 (CET) Date: Tue, 9 Feb 2021 10:36:42 +0100 From: Christoph Hellwig To: Greg KH Cc: obayashi.yoshimasa@socionext.com, sumit.garg@linaro.org, hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, daniel.thompson@linaro.org Subject: Re: DMA direct mapping fix for 5.4 and earlier stable branches Message-ID: <20210209093642.GA1006@lst.de> References: <27bbe35deacb4ca49f31307f4ed551b5@SOC-EX02V.e01.socionext.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 09, 2021 at 10:23:12AM +0100, Greg KH wrote: > > From the view point of ZeroCopy using DMABUF, is 5.4 not > > mature enough, and is 5.10 enough mature ? > > This is the most important point for judging migration. > > How do you judge "mature"? > > And again, if a feature isn't present in a specific kernel version, why > would you think that it would be a viable solution for you to use? I'm pretty sure dma_get_sgtable has been around much longer and was supposed to work, but only really did work properly for arm32, and for platforms with coherent DMA. I bet he is using non-coherent arm64, and it would be broken for other drivers there as well if people did test them, which they apparently so far did not.