From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755527Ab3DQJzJ (ORCPT ); Wed, 17 Apr 2013 05:55:09 -0400 Received: from relay3.sgi.com ([192.48.152.1]:33375 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753260Ab3DQJzH (ORCPT ); Wed, 17 Apr 2013 05:55:07 -0400 Date: Wed, 17 Apr 2013 04:55:01 -0500 From: Robin Holt To: "H. Peter Anvin" Cc: Robin Holt , Ingo Molnar , Russ Anderson , Shawn Guo , Oleg Nesterov , Andrew Morton , Joe Perches , Lai Jiangshan , Linus Torvalds , Linux Kernel Mailing List , Michel Lespinasse , "Paul E. McKenney" , Paul Mackerras , Peter Zijlstra , "rusty@rustcorp.com.au" , Tejun Heo , the arch/x86 maintainers , Thomas Gleixner Subject: Re: [Patch -v4 4/4] Make reboot_cpuid a kernel parameter. other cpus. Message-ID: <20130417095501.GD3658@sgi.com> References: <20130416095641.GL3658@sgi.com> <20130416100439.GM3672@sgi.com> <20130416124411.GP3658@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130416124411.GP3658@sgi.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 16, 2013 at 07:44:12AM -0500, Robin Holt wrote: > On Tue, Apr 16, 2013 at 05:05:45AM -0700, H. Peter Anvin wrote: > > Why not just support the existing syntax everywhere? > > I have not given it much consideration, but IIRC, the other arches that > were using reboot= were only looking for an 'h' or something like that. > > I will consider making the syntax parse reboot=s#### when I get to > the office. Yesterday was rather disruptive and I did not get to this. I have given it some thought this morning. Generally speaking, I don't like the feel of this for two reasons. First, having two different places that are parsing reboot= and its related difficulty in documenting it. Second, we lose the /sys/ file. Some background. First, arm. It already has a reboot=. That gets passed to the reboot sub-arch function. It looks like it is ignored, but I am very uncertain of that as it is passed into an assembly routine. Second unicore. It parses as reboot=. That gets ignored. Now the meat of my question. The Documentation/kernel-parameters.txt file indicates reboot= is handled by the arch and are of the format [,[,...]]. I suppose we could have both an arch and generic kernel handler for __setup("reboot=",...) where the generic kernel one just handles the s###, but that seems really different from how everything else is done. I could not find one instance where a both an arch and the kernel proper both parsed the same command-line parameter. I did not spend the time to see if having two __setup() declarations would work. Additionally, the __setup("... mechanism loses the nice feature the core_param gives us in that there is a /sys/ file now available which allows us to easily change that setting on the running system. Are you really sure you want me to do more than I already have. This really feels _VERY_ wrong to me. Maybe I misunderstood your direction. Thanks, Robin