From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1EurfE-0002eG-BM for qemu-devel@nongnu.org; Fri, 06 Jan 2006 08:29:53 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1EurfB-0002dG-9I for qemu-devel@nongnu.org; Fri, 06 Jan 2006 08:29:51 -0500 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Eurf9-0002d1-7n for qemu-devel@nongnu.org; Fri, 06 Jan 2006 08:29:47 -0500 Received: from [65.74.133.5] (helo=mail.codesourcery.com) by monty-python.gnu.org with esmtp (TLS-1.0:DHE_RSA_3DES_EDE_CBC_SHA:24) (Exim 4.34) id 1Eurgt-0002D1-Tf for qemu-devel@nongnu.org; Fri, 06 Jan 2006 08:31:36 -0500 From: Paul Brook Subject: Re: [Qemu-devel] PCI access virtualization Date: Fri, 6 Jan 2006 13:27:47 +0000 References: <1136456096.4464.90.camel@gimli> <200601051810.54954.paul@codesourcery.com> <200601060154.45653.mark.williamson@cl.cam.ac.uk> In-Reply-To: <200601060154.45653.mark.williamson@cl.cam.ac.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200601061327.48828.paul@codesourcery.com> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Mark Williamson Cc: qemu-devel@nongnu.org > > IIUC PCI cards don't really have "DMA engines" as such. The PCI bridge > > just maps PCI address space onto physical memory. A Busmaster PCI device > > can then make arbitrary acceses whenever it wants. I expect the default > > mapping is a 1:1 mapping of the first 4G of physical ram. > > I was under the impression that the on-card bus-mastering engines were > often one of a few standard designs - this was suggested to me by someone > more knowledgeable than myself but must admit I don't have any hard > evidence that it's the case ;-) What about 64-bit systems that use an IOMMU? Don't they already have a 64-bit physical -> 32-bit IO address space mapping? I don't know if this mapping is per-bus or system global. Paul