From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-in-01.arcor-online.net (mail-in-02.arcor-online.net [151.189.21.42]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx.arcor.de", Issuer "Thawte Premium Server CA" (verified OK)) by ozlabs.org (Postfix) with ESMTP id 363FF67B9A for ; Fri, 22 Sep 2006 01:31:30 +1000 (EST) In-Reply-To: <20060921133707.GA29137@gate.crashing.org> References: <17680.30367.157642.674242@cargo.ozlabs.ibm.com> <20060920012042.GA28489@mag.az.mvista.com> <1158721828.3043.13.camel@vader.jdub.homelinux.org> <1158787957.6002.307.camel@localhost.localdomain> <20060920215738.GC24809@mag.az.mvista.com> <20060921133707.GA29137@gate.crashing.org> Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: <1CA5168F-9ECA-4AA2-92AE-F86579245855@kernel.crashing.org> From: Segher Boessenkool Subject: Re: [PATCH] Start arch/powerpc/boot code reorganization Date: Thu, 21 Sep 2006 17:31:18 +0200 To: Matt Porter Cc: linuxppc-dev@ozlabs.org, Paul Mackerras List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , > On PPC44x (and other PowerPC processors) the number of address cells > to represent a virtual address and a physical address differ due the > 36-bits of physical address space. The number of virtual address cells is always 1. A cell isn't always 32-bits though. Want more confusion? Lots of properties are called "-cells" etc., but those names are historical; the proper name for the things encoded in properties is "32-bit integers". > Regardless of the name of the > new property, it should be defined to allow a different number of > address cells to represent an address in virtual address space. How about you check whether the "64-bit" property exists in the CPU nodes? >> (*) This isn't strictly correct, but OF doesn't describe the size of >> virtual addresses anywhere. In practice, it's the same as the size >> of physical addresses always. Oh, and the name "virtual" isn't >> correct >> in PowerPC-speak anyway, heh. > > Actually, in practice, it's not always the same size as a physical > address. We have 36-bit physical addressing systems in the real world. Darn, and you have #address-cells = 2 in the root node? It's allowed, sure. > FWIW, I'd be happy with this property name or fw,address. When we > discussed this on IRC the thought was to conform to what already > existed for this purpose in the OF spec. Since the address prop sounds > like it will confuse some people I think it makes sense to add a > new property (might as well just throw out the spec :P). But if you do make something new, you'll have to make it better than what you're replacing, or what's the point :-) Segher