From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752862Ab3EUJET (ORCPT ); Tue, 21 May 2013 05:04:19 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:33140 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752467Ab3EUJER (ORCPT ); Tue, 21 May 2013 05:04:17 -0400 Date: Tue, 21 May 2013 10:03:36 +0100 From: Will Deacon To: Chen Gang Cc: Geert Uytterhoeven , Catalin Marinas , Arnd Bergmann , Tony Lindgren , Santosh Shilimkar , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] arm64: kernel: need extern variable 'screen_info' for related driver using. Message-ID: <20130521090336.GC10453@mudshark.cambridge.arm.com> References: <5199B7D6.40907@asianux.com> <20130520091008.GB31359@mudshark.cambridge.arm.com> <519AE6D7.1090401@asianux.com> <519B278B.6030708@asianux.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <519B278B.6030708@asianux.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 21, 2013 at 08:51:39AM +0100, Chen Gang wrote: > On 05/21/2013 02:57 PM, Geert Uytterhoeven wrote: > > On Tue, May 21, 2013 at 5:15 AM, Chen Gang wrote: > >>> >> I think it would be better if we added a something like > >>> >> CONFIG_HAVE_VGA_CONSOLE, which VGA_CONSOLE can then depend on. Architectures > >>> >> like x86 can then select the former, and we can remove the long list of > >>> >> architectures from the current option. > >> > > >> > I guess your meaning is: > >> > > >> > under arm64, actually, need not support 'VGA_CONSOLE', and 'screen_info' is useless. > >> > So better to define 'CONFIG_HAVE_VGA_CONSOLE' which 'VGA_CONSOLE' can depend on it, and in arm64, we do not define CONFIG_HAVE_VGA_CONSOLE. > >> > > >> > Is it correct ? > > No, you missed "and we can remove the long list of architectures from the > > current option". > > > > OK, thanks. > > Is it correct: "it is unnecessary to add 'screen_info' to the code, for > arm64 will never support 'VGA_CONSOLE'" ? We can add the screen_info if and when we need to support a VGA console. In the meantime, let's not add things on a whim. > >> > If so, I recommend to add depend item for VGA_CONSOLE directly: > > I strongly support CONFIG_HAVE_VGA_CONSOLE. > > For me, I still recommend add 'ARM64' in the long list of architectures > for 'VGA_CONSOLE', I have 3 reasons, please check: > > a. current implementation only changes one area which only related with > arm64 and 'VGA_CONSOLE', but if use 'CONFIG_HAVE_VGA_CONSOLE', that will > touch many multiple platforms dependency, at least we need discuss about > it with multiple platforms guys for it, firstly. That's a weak argument. You might as well propose the cleanup and see what people say. > b. We can find some cases to use CONFIG_HAVE_* as dpend on, but I can > not find any cases which let CONFIG_'samename' depend on > CONFIG_HAVE_'samename'. Erm. PERF_EVENTS, BPF_JIT, IDE, ...? > c. The original way still has effect, although it seems not quit > beautiful, but it is correct and still clear for readers, it is still > sustainable. Sure, it works, but we're just contributing to the mess that's been built up ever time another architecture has done the same thing. It's not hard to try and clean it up. Will