From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758468AbYHKWPi (ORCPT ); Mon, 11 Aug 2008 18:15:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752122AbYHKWP3 (ORCPT ); Mon, 11 Aug 2008 18:15:29 -0400 Received: from gw.goop.org ([64.81.55.164]:53134 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752113AbYHKWP3 (ORCPT ); Mon, 11 Aug 2008 18:15:29 -0400 Message-ID: <48A0B9EB.9020709@goop.org> Date: Mon, 11 Aug 2008 15:15:07 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.16 (X11/20080723) MIME-Version: 1.0 To: benh@kernel.crashing.org CC: Andrew Morton , ehabkost@redhat.com, x86@kernel.org, linux-kernel@vger.kernel.org, Paul Mackerras Subject: Re: [PATCH 1/2] add phys_addr_t for holding physical addresses References: <489B6B40.5050705@goop.org> <20080807145648.ab3dfa90.akpm@linux-foundation.org> <489B72C3.30603@goop.org> <20080807162741.8dfcd336.akpm@linux-foundation.org> <489B8908.2010007@goop.org> <20080807170617.79ca3ce7.akpm@linux-foundation.org> <48A0954E.20400@goop.org> <1218491896.8041.9.camel@pasglop> In-Reply-To: <1218491896.8041.9.camel@pasglop> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Benjamin Herrenschmidt wrote: > On Mon, 2008-08-11 at 12:38 -0700, Jeremy Fitzhardinge wrote: > >> Add a kernel-wide "phys_addr_t" which is guaranteed to be able to hold >> any physical address. By default it equals the word size of the >> architecture, but a 32-bit architecture can set ARCH_PHYS_ADDR_T_64BIT >> if it needs a 64-bit phys_addr_t. >> > > I've been wondering for some time why can't we make phys_addr_t and > resource_size_t the same thing... I don't like having two ARCH_* thing > especially since I believe the one for resources is already what we > want. > I made the same argument, but Andrew thinks they're conceptually distinct. It is theoretically possible you might have a system with >4G memory, but all io resources < 4G, so you'd have resource_size_t 32-bits, while having 64-bit physical addresses. You can configure such a thing, but I don't know if it's 1) useful or 2) used. J