From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Brook Subject: Re: [Qemu-devel] [PATCH 2/6] PCI DMA API Date: Sun, 30 Mar 2008 10:18:14 +0000 Message-ID: <200803301118.15663.paul@codesourcery.com> References: <1206827760-4566-1-git-send-email-aliguori@us.ibm.com> <1206827760-4566-2-git-send-email-aliguori@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel@lists.sourceforge.net, Marcelo Tosatti , Aurelien Jarno To: qemu-devel@nongnu.org Return-path: In-Reply-To: <1206827760-4566-2-git-send-email-aliguori@us.ibm.com> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org On Saturday 29 March 2008, Anthony Liguori wrote: > This patch introduces a PCI DMA API and some generic code to support other > DMA APIs. Two types are introduced: PhysIOVector and IOVector. A DMA API > maps a PhysIOVector, which is composed of target_phys_addr_t, into an > IOVector, which is composed of void *. Devices should not be using IOVector. They should either use the DMA copy routines to copy from a PhysIOVector into a local buffer, or they should pass a PhysIOVector to a block/network read/write routine. The DMA API should allow devices to be agnostic about how DMA is implemented. They should not be trying to manually implement zero copy. > This enables zero-copy IO to be preformed without introducing assumptions > of phys_ram_base. This API is at the PCI device level to enable support of > per-device IOMMU remapping. By my reading it *requires* bridges be zero-copy. For big-endian targets we need to ability to byteswap accesses. Some description (in the form of source comments) of how it's meant to be used would also be helpful. Paul ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace