Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758858AbXJYGmX (ORCPT ); Thu, 25 Oct 2007 02:42:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754633AbXJYGmO (ORCPT ); Thu, 25 Oct 2007 02:42:14 -0400 Received: from extu-mxob-2.symantec.com ([216.10.194.135]:37792 "EHLO extu-mxob-2.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754153AbXJYGmO (ORCPT ); Thu, 25 Oct 2007 02:42:14 -0400 Date: Thu, 25 Oct 2007 07:40:45 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@blonde.wat.veritas.com To: Arjan van de Ven cc: Jens Axboe , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2.6.24-rc1] fix sg_phys to use dma_addr_t In-Reply-To: <20071024192949.346687ed@laptopd505.fenrus.org> Message-ID: References: <20071024192949.346687ed@laptopd505.fenrus.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1536 Lines: 32 On Wed, 24 Oct 2007, Arjan van de Ven wrote: > > Signed-off-by: Hugh Dickins > > --- > > Whether this is a complete patch, suitable for all architectures, > > I'm not sure: it builds, boots and runs correctly on the x86_32 box > > in question, but you'll be a lot wiser than me about using dma_addr_t > > for everyone. (Seems a bit of a shame to include here, > > when I think all arches already get to include it one way or another, > > typically via asm/scatterlist.h; but I guess it's safest to repeat > > it.) > > there is a problem with this... sg_phys doesn't return an actual *dma* > address.... at least not an address you can give to the device. > Using dma_addr_t is thus a bit misleading..... True. Perhaps sg_phys() should use its own sg_phys_addr_t, defined or typedefed to be the same as dma_addr_t. But would this inline function then be the only place in the tree which uses that type? If so, then it'd probably be better just to let sg_phys() carry on using dma_addr_t, but insert a comment there to make your point. But I'll leave it to Jens to fix up the patch appropriately: for all I know, there might be arches on which using dma_addr_t there actually does the wrong thing - I don't think so, but I know too little about it. Hugh - 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/