From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Joerg Roedel" Subject: Re: [PATCH 3/8] KVM: PVDMA Guest: Guest-side routines for paravirtualized DMA Date: Mon, 12 Nov 2007 17:00:23 +0100 Message-ID: <20071112160023.GG6466@amd.com> References: <609d5d611a5fb58ab5a7184be7b6d29494023ba0.1194445109.git.amit.shah@qumranet.com> <20071112105001.GF3299@rhun.haifa.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Muli Ben-Yehuda" Return-path: In-Reply-To: <20071112105001.GF3299-WD1JZD8MxeCTrf4lBMg6DdBPR1lH4CV8@public.gmane.org> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org On Mon, Nov 12, 2007 at 12:50:01PM +0200, Muli Ben-Yehuda wrote: > On Wed, Nov 07, 2007 at 04:21:04PM +0200, Amit Shah wrote: > > > We make the dma_mapping_ops structure to point to our structure so > > that every DMA access goes through us. (This is the reason this only > > works for 64-bit guest. 32-bit guest doesn't yet have a dma_ops > > struct.) > > I need the same facility for Calgary for falling back to swiotlb if a > translation is disabled on some slot, and IB needs the same facility > for some IB adapters (e.g., ipath). Perhaps it's time to consider > stackable dma-ops (unless someone has a better idea...). Stackable dma-ops sounds good to me. The only problem is that there is a performance penalty for devices handled on the bottom of the stack. But the alternative I can think of, a per-device dma-ops structure, uses more memory and is much more intrusive to the driver core. So I am fine with a stackable solution. Joerg -- | AMD Saxony Limited Liability Company & Co. KG Operating | Wilschdorfer Landstr. 101, 01109 Dresden, Germany System | Register Court Dresden: HRA 4896 Research | General Partner authorized to represent: Center | AMD Saxony LLC (Wilmington, Delaware, US) | General Manager of AMD Saxony LLC: Dr. Hans-R. Deppe, Thomas McCoy ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/