Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764194AbXFAU0Q (ORCPT ); Fri, 1 Jun 2007 16:26:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762605AbXFAU0F (ORCPT ); Fri, 1 Jun 2007 16:26:05 -0400 Received: from one.firstfloor.org ([213.235.205.2]:60054 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762528AbXFAU0C (ORCPT ); Fri, 1 Jun 2007 16:26:02 -0400 Date: Fri, 1 Jun 2007 22:26:01 +0200 From: Andi Kleen To: Rik van Riel Cc: Andi Kleen , Andrew Vasquez , Christoph Hellwig , linux-kernel Subject: Re: [PATCH] quiet down swiotlb warnings Message-ID: <20070601202601.GM7217@one.firstfloor.org> References: <466057B1.9090309@redhat.com> <20070601181225.GA16460@infradead.org> <20070601193703.GI7217@one.firstfloor.org> <466075D1.8080807@redhat.com> <20070601194734.GJ7217@one.firstfloor.org> <20070601200049.GK12143@andrew-vasquezs-computer.local> <20070601201444.GK7217@one.firstfloor.org> <46607F96.7060200@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <46607F96.7060200@redhat.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1156 Lines: 27 On Fri, Jun 01, 2007 at 04:20:38PM -0400, Rik van Riel wrote: > Andi Kleen wrote: > >On Fri, Jun 01, 2007 at 01:00:49PM -0700, Andrew Vasquez wrote: > >>yes, the card can support 64bit DMA transfers. but in this case the > >>'required' DMA mask returned from dma_get_required_mask() states that a > >>32bit mask would suffice. > > > >That's a bug in the kernel then that needs to be fixed. Find out > >why it does that and change it. Don't fix the symptoms, fix the root cause. > > The system in question only has 2GB of memory. > > Why would it need to do 64 bit DMA? It doesn't. But it definitely doesn't need swiotlb either. Normally swiotlb doesn't even try to bounce when dma mask is <= end_pfn so something must be very wrong in your kernel. It definitely isn't a mainline kernel. If this happens in Xen then Xen just needs fixing -- it should not try to bounce when the normal kernel wouldn't. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/