From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758902Ab0JUXYM (ORCPT ); Thu, 21 Oct 2010 19:24:12 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:37866 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751754Ab0JUXYL (ORCPT ); Thu, 21 Oct 2010 19:24:11 -0400 Date: Thu, 21 Oct 2010 16:24:10 -0700 From: Andrew Morton To: Mike Frysinger Cc: Luca Barbieri , linux-kernel@vger.kernel.org Subject: Re: [PATCH] lib/atomic64_test: do not build on non-atomic64 systems Message-Id: <20101021162410.5c0d6720.akpm@linux-foundation.org> In-Reply-To: References: <1287250035-30404-1-git-send-email-vapier@gentoo.org> <20101021150250.f6499506.akpm@linux-foundation.org> <201010211823.38287.vapier@gentoo.org> <20101021155528.b3d6d027.akpm@linux-foundation.org> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.9; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 21 Oct 2010 19:04:36 -0400 Mike Frysinger wrote: > On Thu, Oct 21, 2010 at 18:55, Andrew Morton wrote: > > On Thu, 21 Oct 2010 18:23:37 -0400 Mike Frysinger wrote: > >> On Thursday, October 21, 2010 18:02:50 Andrew Morton wrote: > >> > On Sat, 16 Oct 2010 13:27:15 -0400 Mike Frysinger wrote: > >> > > If the arch doesn't provide atomic64 functionality (there are quite a > >> > > few), then don't bother trying to build this test. > >> > > >> > I don't get it. __If the arch doesn't implement atomic64 then this file > >> > will get zillions of build errors, won't it? > >> > >> ... which is why i added the ifdef protection > > > > So the changelog was poor. __Please write complete changelogs so I need > > to have this sort of conversation less often? > > the changelog seems pretty clear to me. arch doesnt provide atomic64, > so dont build code that uses atomic64. That the patch fixes build errors is rather important information. > > I know that. __But the standard way for an architecture to indicate to > > the core that it impements a feature is for it to define CONFIG_HAVE_*. > > Picking some related #define which architectures happen to implement > > is atypical and unexpected. > > > > Will it cause problems? __Probably not, unless the arch goes and defines > > ATOMIC64_INIT without actually implementing atomic64. __But it's > > atypical and unexpected and, yes, lazy! > > you can say "lazy" all you like. i dont see the point in going that route. Try grep HAVE arch/x86/Kconfig If all of those were instead to use some random #define which the particular feature happened to define in some header file then we would have a mess on our hands. There's your point.