From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gerd Hoffmann Subject: Re: VP problematic for backend drivers on IA64? Date: Wed, 25 Jan 2006 17:24:56 +0100 Message-ID: <43D7A658.4020105@suse.de> References: <20060120015505.GB8504@granada.merseine.nu> <43D75311.3040808@suse.de> <20060125143732.GE24849@granada.merseine.nu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20060125143732.GE24849@granada.merseine.nu> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Muli Ben-Yehuda Cc: "Magenheimer, Dan (HP Labs Fort Collins)" , xen-devel , okrieg@us.ibm.com List-Id: xen-devel@lists.xenproject.org Hi, > I think it's a pretty ugly hack; struct page has a very specific > meaning in Linux. Minimizing changes in Linux by subverting this > meaning does not strike me as the right thing to do. Well, not exactly nice indeed, but any other solution involves touching all block drivers ... > at all - Linux is never going to look at the page (kmap it). Having Depends. If it's actually DMA'ing directly it doesn't, which should be true in 99% of all cases. But there are some corner cases: If the block layer needs bounce buffers it will attempt to kmap() the page to copy the data. The same is true for drivers which don't DMA (floppy.c for example). cheers, Gerd -- Gerd 'just married' Hoffmann I'm the hacker formerly known as Gerd Knorr. http://www.suse.de/~kraxel/just-married.jpeg