From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sasl.smtp.pobox.com (a-sasl-fastnet.sasl.smtp.pobox.com [207.106.133.19]) by ozlabs.org (Postfix) with ESMTP id A18E6DDF00 for ; Tue, 3 Jun 2008 07:26:57 +1000 (EST) Date: Mon, 2 Jun 2008 16:26:32 -0500 From: Nathan Lynch To: Segher Boessenkool Subject: Re: [PATCH] [POWERPC] 85xx: Add next-level-cache property Message-ID: <20080602212632.GA7475@localdomain> References: <1212180199-968-1-git-send-email-galak@kernel.crashing.org> <1212180199-968-2-git-send-email-galak@kernel.crashing.org> <165963514fdb3980898f3babaad546a9@kernel.crashing.org> <8945FFBA-5552-4CF4-B185-8FDD7885B744@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Cc: ppc-dev list , Yoder Stuart List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Segher Boessenkool wrote: >>> >>> The PowerPC binding defines an "l2-cache" property for this (it >>> points from CPU node to L2 cache node, from L2 cache node to L3 >>> cache node, from L3 cache node to L4 cache node, etc.) >> >> So looking at the PPC binding its not terrible clear about "l3-cache" >> being a valid property. > > It isn't. The property is called "l2-cache" at every level. > >> I believe the discussion w/ePAPR was to create something a bit more >> generic and clarify/update the PPC binding. > > Nasty. Sure, "l2-cache" isn't the nicest name to point to deeper > cache levels, but introducing a new property with (substantially) > the same semantics is worse. The semantics appear to be identical, even. > There really shouldn't be a new property name until new functionality > is introduced. For example, it could allow to describe more than one > cache at each level (the current binding already allows more than one > parent for each cache, but only one child; and cache hierarchies like > that actually exist). > >> I'm going to stick with the new binding as we don't use this linking >> currently. > > Dunno what's the best thing to do here. If you don't need the > functionality yet, it might be best to postpone putting either > property in there. Sigh, what a mess. Does existing practice count for anything? IBM pseries firmware uses the l2-cache property as described in the PowerPC binding.