Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932108Ab0BYDTU (ORCPT ); Wed, 24 Feb 2010 22:19:20 -0500 Received: from hera.kernel.org ([140.211.167.34]:59572 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758865Ab0BYDTQ (ORCPT ); Wed, 24 Feb 2010 22:19:16 -0500 Message-ID: <4B85EE88.5050506@kernel.org> Date: Thu, 25 Feb 2010 12:29:12 +0900 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091130 SUSE/3.0.0-1.1.1 Thunderbird/3.0 MIME-Version: 1.0 To: Yuhong Bao CC: hancockrwd@gmail.com, david-b@pacbell.net, greg@kroah.com, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Subject: Re: [PATCH 2.6.34] ehci-hcd: add option to enable 64-bit DMA support References: <4B7CAF95.6020306@gmail.com> <20100218052223.GA13254@kroah.com> <51f3faa71002181633w1649a648s37ae73da342d0c3f@mail.gmail.com> <201002192139.46189.david-b@pacbell.net> <51f3faa71002192315ia84786eo1138bf9ab3417f2d@mail.gmail.com> <51f3faa71002231626q1eb62adeo660c282418f0e01@mail.gmail.com>,<4B85E038.20905@kernel.org> In-Reply-To: X-Enigmail-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Thu, 25 Feb 2010 03:19:13 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1173 Lines: 30 Hello, On 02/25/2010 12:15 PM, Yuhong Bao wrote: >> (following thread from the ATA side) I'm with Greg on this. USB2.0 is >> quite slow on today's standard and most 64bit machines now have IOMMU >> of some kind anyway. > > Except that unfortunately, Intel with Lynnfield and Clarkdale decided > to do market segmentation on the VT-d feature. > This could be done because both have an integrated northbridge. > With Lynnfield, the very common Core i5 750 CPU do not support VT-d, > but the Core i7 800 series does. > With Clarkdale, the very common Core i3 500 series do not support VT-d, > but the Core i5 600 series does, except the 661. > Not to mention that in the Core 2 generation, VT-d was available only > on Q35/Q45/X38/X48 chipsets. Arghhh.... I hate when intel pulls this type of 'product differentiation' stunts. At any rate, I'm doubtful swiotlb'ing for usb2.0 would be noticeable at all. Thanks. -- tejun -- 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/