From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263077AbTEVSgd (ORCPT ); Thu, 22 May 2003 14:36:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263078AbTEVSgd (ORCPT ); Thu, 22 May 2003 14:36:33 -0400 Received: from meryl.it.uu.se ([130.238.12.42]:6133 "EHLO meryl.it.uu.se") by vger.kernel.org with ESMTP id S263077AbTEVSgc (ORCPT ); Thu, 22 May 2003 14:36:32 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16077.7101.339611.256918@gargle.gargle.HOWL> Date: Thu, 22 May 2003 20:49:33 +0200 From: mikpe@csd.uu.se To: William Lee Irwin III Cc: akpm@digeo.com, linux-kernel@vger.kernel.org Subject: Re: arch/i386/kernel/mpparse.c warning fixes In-Reply-To: <20030522183608.GV8978@holomorphy.com> References: <20030522155320.GP29926@holomorphy.com> <16076.62927.525714.113342@gargle.gargle.HOWL> <20030522162305.GT8978@holomorphy.com> <16077.5909.155004.502440@gargle.gargle.HOWL> <20030522183608.GV8978@holomorphy.com> X-Mailer: VM 6.90 under Emacs 20.7.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org William Lee Irwin III writes: > 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. Ah, so it's a workaround to silence a compiler warning on char > 256. Frankly, I'd rather see a cast there in this case. I.e., (unsigned int)m->mpc_apicid >= MAX_APICS or something like that, with a suitable comment.