From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263056AbTEVSXY (ORCPT ); Thu, 22 May 2003 14:23:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263062AbTEVSXY (ORCPT ); Thu, 22 May 2003 14:23:24 -0400 Received: from holomorphy.com ([66.224.33.161]:48269 "EHLO holomorphy") by vger.kernel.org with ESMTP id S263056AbTEVSXQ (ORCPT ); Thu, 22 May 2003 14:23:16 -0400 Date: Thu, 22 May 2003 11:36:08 -0700 From: William Lee Irwin III To: mikpe@csd.uu.se Cc: akpm@digeo.com, linux-kernel@vger.kernel.org Subject: Re: arch/i386/kernel/mpparse.c warning fixes Message-ID: <20030522183608.GV8978@holomorphy.com> Mail-Followup-To: William Lee Irwin III , mikpe@csd.uu.se, akpm@digeo.com, linux-kernel@vger.kernel.org References: <20030522155320.GP29926@holomorphy.com> <16076.62927.525714.113342@gargle.gargle.HOWL> <20030522162305.GT8978@holomorphy.com> <16077.5909.155004.502440@gargle.gargle.HOWL> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <16077.5909.155004.502440@gargle.gargle.HOWL> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org William Lee Irwin III writes: >> m->mpc_apicid is an 8-bit type; MAX_APICS can be 256. The above fix >> properly compares two integral expressions of equal width. On Thu, May 22, 2003 at 08:29:41PM +0200, mikpe@csd.uu.se wrote: > In the original "_>_", the 8-bit mpc_apicid is implicitly converted to int > before the comparison, as part of the "integer promotions" in the "usual > arithmetic conversions" (C standard lingo). The same happens in your "_-_<=0". > So what's the benefit of the rewrite? It removes a warning about comparisons being always true or false by virtue of the limited range of a type. William Lee Irwin III writes: >> Also, as MAX_APICS-1 is reserved for the broadcast physical APIC ID >> (it's 0xF for serial APIC and 0xFF for xAPIC) the small semantic change >> here is correct. On Thu, May 22, 2003 at 08:29:41PM +0200, mikpe@csd.uu.se wrote: > No argument there, except that ">=" gets the job done in a cleaner way. This is actually massively confused anyway. It gets physical APIC ID checks wrong for sparse xAPIC's on mach-default. But that's another issue. -- wli