Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936083Ab3DRBZl (ORCPT ); Wed, 17 Apr 2013 21:25:41 -0400 Received: from relay1.sgi.com ([192.48.179.29]:41936 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935094Ab3DRBZk (ORCPT ); Wed, 17 Apr 2013 21:25:40 -0400 Date: Wed, 17 Apr 2013 20:25:39 -0500 From: Robin Holt To: "H. Peter Anvin" Cc: Robin Holt , Ingo Molnar , "Srivatsa S. Bhat" , Russ Anderson , Linux Kernel Mailing List , the arch/x86 maintainers Subject: Re: [PATCH -v5 5/5] Make reboot_cpuid a kernel parameter. Message-ID: <20130418012539.GN3658@sgi.com> References: <1366224198-49485-1-git-send-email-holt@sgi.com> <1366224198-49485-6-git-send-email-holt@sgi.com> <516EF9DE.6000707@zytor.com> <20130417194836.GK3658@sgi.com> <516EFF3D.4040506@zytor.com> <20130417201533.GL3658@sgi.com> <20130418001726.GM3658@sgi.com> <516F40C5.40409@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <516F40C5.40409@zytor.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 Content-Length: 2295 Lines: 50 On Wed, Apr 17, 2013 at 05:39:33PM -0700, H. Peter Anvin wrote: > On 04/17/2013 05:17 PM, Robin Holt wrote: > > > > There are 4 items being parsed out of reboot= for x86: > > - reboot_mode w[arm] | c[old] > > - reboot_cpu s[mp]#### > > - reboot_type b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci] > > - reboot_force f[orce] > > > > This seems like a lot to push into the generic kernel just to make it > > appear consistent when there will be no real cross arch consistency. > > > > Contrast that with: > > 1) New kernel parameter (reboot_cpu) which is clear and concise, uses standard > > parsing methods. > > 2) Backwards compatibility in that a user with an existing (broken) reboot=s32 > > on the command line will set reboot_cpu unless both were specified, in which > > case reboot_cpu takes precedence. > > > > What is so fundamentally wrong with that? It accomplishes exactly what > > you had asked for in that existing users are not broken. We are introducing > > a new functionality in the general kernel. Why not introduce a new parameter > > associated with that functionality. > > > > You are confusing implementation with interface. That is what is so > fundamentally wrong with that. You really, really don't want to change > interface unless the world will end if you don't. > > As far as why centralize -- the main concern I have is that someone > might try to introduce an arch-specific reboot= which is *syntactically* > different, which is yet again really awful from a user perspective. Yes and no. I am saying that the interface is garbage and already specified as arch specific. You are asking me to take that garbage interface and promote it to a general interface which will force us to implement it in a completely crappy way. Compare that with introducing a new interface which is concise and then providing backwards compatibility. Add to that the fact, I don't need to pollute the kernel with some poorly done x86 interface and leave that cruft for others to clean up. Thanks, Robin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/