Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751434AbWCOWId (ORCPT ); Wed, 15 Mar 2006 17:08:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751584AbWCOWId (ORCPT ); Wed, 15 Mar 2006 17:08:33 -0500 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:8152 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S1751434AbWCOWIc (ORCPT ); Wed, 15 Mar 2006 17:08:32 -0500 To: Benjamin LaHaise Cc: Kumar Gala , Vivek Goyal , linux kernel mailing list , Fastboot mailing list , Morton Andrew Morton , gregkh@suse.de Subject: Re: [RFC][PATCH] Expanding the size of "start" and "end" field in "struct resource" References: <20060315193114.GA7465@in.ibm.com> <20060315205306.GC25361@kvack.org> <46E23BE4-4353-472B-90E6-C9E7A3CFFC15@kernel.crashing.org> <20060315211335.GD25361@kvack.org> <20060315212841.GE25361@kvack.org> From: ebiederm@xmission.com (Eric W. Biederman) Date: Wed, 15 Mar 2006 14:59:54 -0700 In-Reply-To: <20060315212841.GE25361@kvack.org> (Benjamin LaHaise's message of "Wed, 15 Mar 2006 16:28:41 -0500") Message-ID: User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux) 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: 1278 Lines: 30 Benjamin LaHaise writes: > On Wed, Mar 15, 2006 at 02:29:32PM -0700, Eric W. Biederman wrote: >> If the impact is very slight or unmeasurable this means the option >> needs to fall under CONFIG_EMBEDDED, where you can change if >> every last bit of RAM counts but otherwise you won't care. > > But we have a data type that is correct for this usage: dma_addr_t. Actually now that I think back there are machines with < 4GiB of ram with 64bit pci BAR values. It is more common to have 32bit values BAR values and > 4GiB of ram. So I don't see dma_addr_t in general being the right choice. Although I do suspect that in most cases dma_addr_t <= the size of what is in struct resource. Nor do I think struct resource is nearly as important when being efficient, as dma_addr_t. struct resource is only used during driver setup which is a very rare event. A few extra instructions there likely will get lost in the noise and most of the will probably be removed because they are in an __init section anyway. Eric - 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/