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=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 F13F1C10F14 for ; Tue, 8 Oct 2019 12:50:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D052720640 for ; Tue, 8 Oct 2019 12:50:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730988AbfJHMuO (ORCPT ); Tue, 8 Oct 2019 08:50:14 -0400 Received: from verein.lst.de ([213.95.11.211]:46671 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730605AbfJHMuN (ORCPT ); Tue, 8 Oct 2019 08:50:13 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id D55AD68B05; Tue, 8 Oct 2019 14:50:08 +0200 (CEST) Date: Tue, 8 Oct 2019 14:50:08 +0200 From: Christoph Hellwig To: Arvind Sankar Cc: Christoph Hellwig , Christoph Hellwig , linux-kernel@vger.kernel.org Subject: Re: ehci-pci breakage with dma-mapping changes in 5.4-rc2 Message-ID: <20191008125008.GA4829@lst.de> References: <20191007175430.GA32537@rani.riverdale.lan> <20191007175528.GA21857@lst.de> <20191007175630.GA28861@infradead.org> <20191007175856.GA42018@rani.riverdale.lan> <20191007183206.GA13589@rani.riverdale.lan> <20191007184754.GB31345@lst.de> <20191007221054.GA409402@rani.riverdale.lan> <20191007235401.GA608824@rani.riverdale.lan> <20191008073210.GB9452@lst.de> <20191008115103.GA463127@rani.riverdale.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191008115103.GA463127@rani.riverdale.lan> 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, Oct 08, 2019 at 07:51:03AM -0400, Arvind Sankar wrote: > What I mean is, do there exist devices (which would necessarily support > 64-bit DMA) that want to DMA using bigger than 4Gb buffers. Eg a GPU > accelerator card with 16Gb of RAM on-board that wants to map 6Gb for DMA > in one go, or 5 accelerator cards that are in one IOMMU domain and want > to simultaneously map 1Gb each. If you allocate more than 32-bits worth of address space the IOMMU address space allocator will dip into 64-bit values if the device dma mask supports that.