Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934319Ab3CTA02 (ORCPT ); Tue, 19 Mar 2013 20:26:28 -0400 Received: from mail-vc0-f173.google.com ([209.85.220.173]:63100 "EHLO mail-vc0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934295Ab3CTA00 (ORCPT ); Tue, 19 Mar 2013 20:26:26 -0400 MIME-Version: 1.0 In-Reply-To: <87hak8qfu5.fsf@rustcorp.com.au> References: <87ehfhtftn.fsf@rustcorp.com.au> <87sj3tsawh.fsf@rustcorp.com.au> <87hak8qfu5.fsf@rustcorp.com.au> From: Lucas De Marchi Date: Tue, 19 Mar 2013 21:26:04 -0300 Message-ID: Subject: Re: [RFC PATCH] Allow optional module parameters To: Rusty Russell Cc: Andy Lutomirski , linux-kernel@vger.kernel.org, Ben Hutchings , linux-kbuild@vger.kernel.org, Jon Masters Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2400 Lines: 59 Hi Rusty, On Mon, Mar 18, 2013 at 11:32 PM, Rusty Russell wrote: > Andy Lutomirski writes: >> On Sun, Mar 17, 2013 at 7:24 PM, Rusty Russell wrote: >>> Andy Lutomirski writes: >>>> On Thu, Mar 14, 2013 at 10:03 PM, Rusty Russell wrote: >>>>> Err, yes. Don't remove module parameters, they're part of the API. Do >>>>> you have a particular example? >>>> >>>> So things like i915.i915_enable_ppgtt, which is there to enable >>>> something experimental, needs to stay forever once the relevant >>>> feature becomes non-experimental and non-optional? This seems silly. > ... >>>> Having the module parameter go away while still allowing the module to >>>> load seems like a good solution (possibly with a warning in the logs >>>> so the user can eventually delete the parameter). >>> >>> Why not do that for *every* missing parameter then? Why have this weird >>> notation where the user must know that the parameter might one day go >>> away? >> >> Fair enough. What about the other approach, then? Always warn if an >> option doesn't match (built-in or otherwise) but load the module >> anyways. > > What does everyone think of this? Jon, Lucas, does this match your > experience? > > Thanks, > Rusty. > > Subject: modules: don't fail to load on unknown parameters. > > Although parameters are supposed to be part of the kernel API, experimental > parameters are often removed. In addition, downgrading a kernel might cause > previously-working modules to fail to load. I agree with this reasoning > > On balance, it's probably better to warn, and load the module anyway. However loading the module anyway would bring at least one drawback: if the user made a typo when passing the option the module would load anyway and he will probably not even look in the log, since there's was no errors from modprobe. For finit_module we could put a flag to trigger this behavior and propagate it to modprobe, but this is not possible with init_module(). I can't think in any other option right now... do you have any? Lucas De Marchi -- 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/