From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030623Ab0B0Si3 (ORCPT ); Sat, 27 Feb 2010 13:38:29 -0500 Received: from sh.osrg.net ([192.16.179.4]:35065 "EHLO sh.osrg.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030419Ab0B0Si2 convert rfc822-to-8bit (ORCPT ); Sat, 27 Feb 2010 13:38:28 -0500 Date: Sun, 28 Feb 2010 03:38:20 +0900 To: hancockrwd@gmail.com Cc: davem@davemloft.net, bzolnier@gmail.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-usb@vger.kernel.org Subject: Re: [RFC PATCH] fix problems with NETIF_F_HIGHDMA in networking drivers From: FUJITA Tomonori In-Reply-To: <51f3faa71002270959o4d1435e3xf67185fccaf50b18@mail.gmail.com> References: <51f3faa71002261908y7cfa62eeicb3e56d5c920887a@mail.gmail.com> <20100227.015350.71138134.davem@davemloft.net> <51f3faa71002270959o4d1435e3xf67185fccaf50b18@mail.gmail.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Message-Id: <20100228033800N.fujita.tomonori@lab.ntt.co.jp> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.0 (sh.osrg.net [192.16.179.4]); Sun, 28 Feb 2010 03:38:21 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 27 Feb 2010 11:59:47 -0600 Robert Hancock wrote: > On Sat, Feb 27, 2010 at 3:53 AM, David Miller wrote: > > From: Robert Hancock > > Date: Fri, 26 Feb 2010 21:08:04 -0600 > > > >> That seems like a reasonable approach to me. Only question is how to > >> implement the check for DMA_64BIT. Can we just check page_to_phys on > >> each of the pages in the skb to see if it's > 0xffffffff ? Are there > >> any architectures where it's more complicated than that? > > > > On almost every platform it's "more complicated than that". > > > > This is the whole issue.  What matters is the final DMA address and > > since we have IOMMUs and the like, it is absolutely not tenable to > > solve this by checking physical address attributes. > > Yeah, physical address isn't quite right. There is a precedent for Probably, you need to check PCI_DMA_BUS_IS_PHYS. From mboxrd@z Thu Jan 1 00:00:00 1970 From: FUJITA Tomonori Subject: Re: [RFC PATCH] fix problems with NETIF_F_HIGHDMA in networking drivers Date: Sun, 28 Feb 2010 03:38:20 +0900 Message-ID: <20100228033800N.fujita.tomonori@lab.ntt.co.jp> References: <51f3faa71002261908y7cfa62eeicb3e56d5c920887a@mail.gmail.com> <20100227.015350.71138134.davem@davemloft.net> <51f3faa71002270959o4d1435e3xf67185fccaf50b18@mail.gmail.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org, bzolnier-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: hancockrwd-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org Return-path: In-Reply-To: <51f3faa71002270959o4d1435e3xf67185fccaf50b18-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org On Sat, 27 Feb 2010 11:59:47 -0600 Robert Hancock wrote: > On Sat, Feb 27, 2010 at 3:53 AM, David Miller w= rote: > > From: Robert Hancock > > Date: Fri, 26 Feb 2010 21:08:04 -0600 > > > >> That seems like a reasonable approach to me. Only question is how = to > >> implement the check for DMA_64BIT. Can we just check page_to_phys = on > >> each of the pages in the skb to see if it's > 0xffffffff ? Are the= re > >> any architectures where it's more complicated than that? > > > > On almost every platform it's "more complicated than that". > > > > This is the whole issue. =A0What matters is the final DMA address a= nd > > since we have IOMMUs and the like, it is absolutely not tenable to > > solve this by checking physical address attributes. >=20 > Yeah, physical address isn't quite right. There is a precedent for Probably, you need to check PCI_DMA_BUS_IS_PHYS. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html