From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261703AbVFKNxS (ORCPT ); Sat, 11 Jun 2005 09:53:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261704AbVFKNxS (ORCPT ); Sat, 11 Jun 2005 09:53:18 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:36585 "EHLO parcelfarce.linux.theplanet.co.uk") by vger.kernel.org with ESMTP id S261701AbVFKNxO (ORCPT ); Sat, 11 Jun 2005 09:53:14 -0400 Date: Sat, 11 Jun 2005 14:54:11 +0100 From: Matthew Wilcox To: Lee Revell Cc: Matthew Wilcox , Arjan van de Ven , Jeff Garzik , mike.miller@hp.com, akpm@osdl.org, axboe@suse.de, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Subject: Re: DMA mapping (was Re: [PATCH] cciss 2.6; replaces DMA masks with kernel defines) Message-ID: <20050611135411.GJ24611@parcelfarce.linux.theplanet.co.uk> References: <20050610143453.GA26476@beardog.cca.cpqcorp.net> <42A9C60E.3080604@pobox.com> <1118436000.6423.42.camel@mindpipe> <1118436306.5272.37.camel@laptopd505.fenrus.org> <1118438253.6423.72.camel@mindpipe> <20050610213003.GI24611@parcelfarce.linux.theplanet.co.uk> <1118444891.6423.130.camel@mindpipe> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1118444891.6423.130.camel@mindpipe> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 10, 2005 at 07:08:11PM -0400, Lee Revell wrote: > b44 needs 30 bit: > > #define B44_DMA_MASK 0x3fffffff > > These seem to be all over the place. I guess it saves a tiny bit of > silicon. Don't these all violate the PCI spec? No, it's permitted. What would violate the PCI spec would be failing to decode the full 32/64 bit address and creating aliases (like 10-bit ISA cards did). This is just a reestriction on which parts of memory a card can DMA to. > Should I just add everything from 24 to 63? Actually, it'd be useful to have a central list of what DMA masks devices really take. It might provide some arguments for changing the zone allocater. -- "Next the statesmen will invent cheap lies, putting the blame upon the nation that is attacked, and every man will be glad of those conscience-soothing falsities, and will diligently study them, and refuse to examine any refutations of them; and thus he will by and by convince himself that the war is just, and will thank God for the better sleep he enjoys after this process of grotesque self-deception." -- Mark Twain