From owner-freebsd-arch@FreeBSD.ORG Tue Jul 1 05:22:16 2003 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7376537B404 for ; Tue, 1 Jul 2003 05:22:16 -0700 (PDT) Received: from duke.cs.duke.edu (duke.cs.duke.edu [152.3.140.1]) by mx1.FreeBSD.org (Postfix) with ESMTP id 27CB343FF7 for ; Tue, 1 Jul 2003 05:22:13 -0700 (PDT) (envelope-from gallatin@cs.duke.edu) Received: from grasshopper.cs.duke.edu (grasshopper.cs.duke.edu [152.3.145.30]) by duke.cs.duke.edu (8.12.9/8.12.9) with ESMTP id h61CM8wV010766 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO); Tue, 1 Jul 2003 08:22:08 -0400 (EDT) Received: (from gallatin@localhost) by grasshopper.cs.duke.edu (8.11.6/8.9.1) id h61CM3H10417; Tue, 1 Jul 2003 08:22:03 -0400 (EDT) (envelope-from gallatin@cs.duke.edu) From: Andrew Gallatin MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16129.31978.982920.826662@grasshopper.cs.duke.edu> Date: Tue, 1 Jul 2003 08:22:02 -0400 (EDT) To: ticso@cicely.de In-Reply-To: <20030701092944.GE90081@cicely12.cicely.de> References: <3EF3C12F.9060303@btc.adaptec.com> <16124.39930.142492.356163@grasshopper.cs.duke.edu> <3EFC9F2D.6020908@btc.adaptec.com> <16124.43999.333761.397624@grasshopper.cs.duke.edu> <3EFCAC7A.6060305@btc.adaptec.com> <16124.45051.919899.414795@grasshopper.cs.duke.edu> <3EFD4755.49BAF150@mindspring.com> <16128.17218.973911.980939@grasshopper.cs.duke.edu> <20030701092944.GE90081@cicely12.cicely.de> X-Mailer: VM 6.75 under 21.1 (patch 12) "Channel Islands" XEmacs Lucid cc: Scott Long cc: freebsd-arch@freebsd.org Subject: Re: API change for bus_dma X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 01 Jul 2003 12:22:17 -0000 Bernd Walter writes: > On Mon, Jun 30, 2003 at 10:03:46AM -0400, Andrew Gallatin wrote: > > The idea is that I want to establish a mapping that can be used many > > times without any driver or kernel attention. I don't want to do > > anything in terms of a system call, or interrupt, etc, to sync the > > cache with the state of the DMA'ed page before a DMA read or after a DMA > > write. > > > > For example, scatter gather mapping on alphas (if FreeBSD supported it > > for PCI devices) would be fine with me since its cache-coherent and > > doesn't require any ddi_dma_sync() operations. > > What makes you shure about alpha dma to be cache-coherent? 7 years of sometimes painful experience with Myrinet on alpha ;) > I'm not shure that the current implementation of _bus_dmamap_sync() > without barriers is correct. Barriers, if present, would be used to flush write buffers in the CPU so they're seen by the cache, not to flush the cache itself. I agree they should be present. Drew