From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4CFAEC5B578 for ; Wed, 3 Jul 2019 07:40:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DFFD621897 for ; Wed, 3 Jul 2019 07:40:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562139653; bh=yL8rvQk/7RHBdVLb2DdwMun9Sw8I91GDa/9/pH2pgfk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=IKA2ODY82mn67K6BVFvjz/J+oD46iho+shcOuczM+4rAMu+WPg989V04fCM+wNd1N cGg9qu79umPtxvGHzWcqView5CUik0aWliAHaj7StUY7CpwG5D7rgZihWSZeROiNsk d2gq6ueOi/4wOC4qYaJ2kythMCc9F7mHYOzCDC4Y= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727019AbfGCHkw (ORCPT ); Wed, 3 Jul 2019 03:40:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:49320 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726670AbfGCHkw (ORCPT ); Wed, 3 Jul 2019 03:40:52 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 779BE21880; Wed, 3 Jul 2019 07:40:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562139650; bh=+dS722UyAM8LRJCnQHjINVT/+tf8dVBhrK0IZ3tm/CM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fBJkFDmxci6Z8zsCWUNvmR0m0RsWAxBygRAjGjX9b32Wg9Dp172aSxOjxbbTX+O8y yXkqIGjViFpsfsRUFuwHgUMhOgdhdh+F4uYafbJehQYBQ4n8xtXcLNfOp1HLA4hs2h AN1+onOF5W8kptSvU+uiCWxt8bc8A3wDT0acUX9E= Date: Wed, 3 Jul 2019 09:40:48 +0200 From: Greg Kroah-Hartman To: Luis Chamberlain Cc: Christoph Hellwig , Brendan Higgins , Cristina Moraru , "vegard.nossum@gmail.com" , Valentin Rothberg , Hannes Reinecke , Sam Ravnborg , Michal Marek , "linux-kernel@vger.kernel.org" , Tom Gundersen , Kay Sievers , Rusty Russell , Andrew Morton , backports@vger.kernel.org, Guenter Roeck , "rafael.j.wysocki" , Dmitry Torokhov , Takashi Iwai , Mauro Carvalho Chehab , Johannes Berg , Hauke Mehrtens , Paul Bolle , Paul Gortmaker , Alexey Khoroshilov , Sathya Prakash Veerichetty , "Martin K. Petersen" , Laurence Oberman , Johannes Thumshirn , Tejun Heo , Jej B , Theodore Ts'o , Daniel Jonsson , Andrzej Wasowski Subject: Re: [RFC PATCH 0/5] Add CONFIG symbol as module attribute Message-ID: <20190703074048.GH3033@kroah.com> References: <1471462023-119645-1-git-send-email-cristina.moraru09@gmail.com> <20160818175505.GM3296@wotan.suse.de> <20160825074313.GC18622@lst.de> <20160825201919.GE3296@wotan.suse.de> <20190627045052.GA7594@lst.de> <20190629084257.GA1227@kroah.com> <20190702205106.GR19023@42.do-not-panic.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190702205106.GR19023@42.do-not-panic.com> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: backports-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: backports@vger.kernel.org On Tue, Jul 02, 2019 at 08:51:06PM +0000, Luis Chamberlain wrote: > On Sat, Jun 29, 2019 at 10:42:57AM +0200, Greg Kroah-Hartman wrote: > > On Fri, Jun 28, 2019 at 11:40:22AM -0700, Luis Chamberlain wrote: > > > On Wed, Jun 26, 2019 at 9:51 PM Christoph Hellwig wrote: > > > > > > > > On Wed, Jun 26, 2019 at 03:21:08PM -0700, Luis Chamberlain wrote: > > > > > On Tue, Feb 5, 2019 at 2:07 PM Luis Chamberlain wrote: > > > > > > In lieu of no Luke Skywalker, if you will, for a large kconfig revamp > > > > > > on this, I'm inclined to believe *at least* having some kconfig_symb > > > > > > exposed for some modules is better than nothing. Christoph are you > > > > > > totally opposed to this effort until we get a non-reverse engineered > > > > > > effort in place? It just seems like an extraordinary amount of work > > > > > > and I'm not quite sure who's volunteering to do it. > > > > > > > > > > > > Other stakeholders may benefit from at least having some config --> > > > > > > module mapping for now. Not just backports or building slimmer > > > > > > kernels. > > > > > > > > > > Christoph, *poke* > > > > > > > > Yes, I'm still totally opposed to a half-backed hack like this. > > > > > > The solution puts forward a mechanism to add a kconfig_symb where we > > > are 100% certain we have a direct module --> config mapping. > > > > > > This is *currently* determined when the streamline_config.pl finds > > > that an object has only *one* associated config symbol associated. As > > > Cristina noted, of 62 modules on a running system 58 of them ended up > > > getting the kconfig_symb assigned, that is 93.5% of all modules on the > > > system being tested. For the other modules, if they did want this > > > association, we could allow a way for modules to define their own > > > KBUILD_KCONF variable so that this could be considered as well, or > > > they can look at their own kconfig stuff to try to fit the model that > > > does work. To be clear, the heuristics *can* be updated if there is > > > confidence in alternative methods for resolution. But since it is > > > reflective of our current situation, I cannot consider it a hack. > > > > > > This implementation is a reflection of our reality in the kernel, and > > > as has been discussed in this thread, if we want to correct the gaps > > > we need to do a lot of work. And *no one* is working towards these > > > goals. > > > > > > That said, even if you go forward with an intrusive solution like the > > > one you proposed we could still use the same kconfig_symb... > > > > > > So no, I don't see this as a hack. It's a reflection as to our current > > > reality. And I cannot see how the kconfig_symb can lie or be > > > incorrect. So in fact I think that pushing this forward also makes the > > > problem statement clearer for the future of what semantics needs to be > > > addressed, and helps us even annotate the problematic areas of the > > > kernel. > > > > > > What negative aspects do you see with this being merged in practice? > > > > I'm trying to see what the actual problem that you are wanting to solve > > here with this. What exactly is it? > > The problem is that there is no current maping of a module to respective > kconfig symbol. That's because it is not just "one" symbol per module. If it were, you can just parse the Makefiles and get that single config option for most modules, right? But even then, multiple options can influence a single module as to what actually gets built into that module. So, I would say, "who really cares"? > > Who needs to determine the > > "singular" configuration option that caused a kernel module to be built > > at the expense of all other options? > > Folks wanting to slim down their kernel build, and users of backports. People who want to "slim" down things are rare, and it's usually worth it to work backwards anyway (see what functionality is needed and then go from there, not look at the modules themselves). Or use a tool like 'make localmodconfig' and trim. > > What can that be used for and who will use it? > > Without a mapping there is no clean way to let you slim down your kernel > using a distro kernel as a base, enabling only those things you really > need. It's hard to determine "what you really need" :) Use localmodconfig and you have a great start, then prune from there. Trying to put _all_ configuration dependencies in a single module isn't going to work, our configuration language does not distill down to that. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe backports" in From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BBEC1C5B578 for ; Wed, 3 Jul 2019 07:40:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8BF1F21897 for ; Wed, 3 Jul 2019 07:40:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562139654; bh=+dS722UyAM8LRJCnQHjINVT/+tf8dVBhrK0IZ3tm/CM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ZckmTKxKXDFhBKYvyPMYBDAX/Xbj6vopeypkY0A1X3wPSPTd6d33mKIKsIbDCKl4w lCyg4ehbBSjrlRXIha32Cczgpjy0E+hTtfNlSMhMjAD8K7FZgiQw7foCIqdIvBwkuo T8yxMfyz+BeMzk1ErG0H+RS1gG5aX1B0xuV3mb2Y= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727221AbfGCHkw (ORCPT ); Wed, 3 Jul 2019 03:40:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:49320 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726670AbfGCHkw (ORCPT ); Wed, 3 Jul 2019 03:40:52 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 779BE21880; Wed, 3 Jul 2019 07:40:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562139650; bh=+dS722UyAM8LRJCnQHjINVT/+tf8dVBhrK0IZ3tm/CM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fBJkFDmxci6Z8zsCWUNvmR0m0RsWAxBygRAjGjX9b32Wg9Dp172aSxOjxbbTX+O8y yXkqIGjViFpsfsRUFuwHgUMhOgdhdh+F4uYafbJehQYBQ4n8xtXcLNfOp1HLA4hs2h AN1+onOF5W8kptSvU+uiCWxt8bc8A3wDT0acUX9E= Date: Wed, 3 Jul 2019 09:40:48 +0200 From: Greg Kroah-Hartman To: Luis Chamberlain Cc: Christoph Hellwig , Brendan Higgins , Cristina Moraru , "vegard.nossum@gmail.com" , Valentin Rothberg , Hannes Reinecke , Sam Ravnborg , Michal Marek , "linux-kernel@vger.kernel.org" , Tom Gundersen , Kay Sievers , Rusty Russell , Andrew Morton , backports@vger.kernel.org, Guenter Roeck , "rafael.j.wysocki" , Dmitry Torokhov , Takashi Iwai , Mauro Carvalho Chehab , Johannes Berg , Hauke Mehrtens , Paul Bolle , Paul Gortmaker , Alexey Khoroshilov , Sathya Prakash Veerichetty , "Martin K. Petersen" , Laurence Oberman , Johannes Thumshirn , Tejun Heo , Jej B , Theodore Ts'o , Daniel Jonsson , Andrzej Wasowski Subject: Re: [RFC PATCH 0/5] Add CONFIG symbol as module attribute Message-ID: <20190703074048.GH3033@kroah.com> References: <1471462023-119645-1-git-send-email-cristina.moraru09@gmail.com> <20160818175505.GM3296@wotan.suse.de> <20160825074313.GC18622@lst.de> <20160825201919.GE3296@wotan.suse.de> <20190627045052.GA7594@lst.de> <20190629084257.GA1227@kroah.com> <20190702205106.GR19023@42.do-not-panic.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190702205106.GR19023@42.do-not-panic.com> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 02, 2019 at 08:51:06PM +0000, Luis Chamberlain wrote: > On Sat, Jun 29, 2019 at 10:42:57AM +0200, Greg Kroah-Hartman wrote: > > On Fri, Jun 28, 2019 at 11:40:22AM -0700, Luis Chamberlain wrote: > > > On Wed, Jun 26, 2019 at 9:51 PM Christoph Hellwig wrote: > > > > > > > > On Wed, Jun 26, 2019 at 03:21:08PM -0700, Luis Chamberlain wrote: > > > > > On Tue, Feb 5, 2019 at 2:07 PM Luis Chamberlain wrote: > > > > > > In lieu of no Luke Skywalker, if you will, for a large kconfig revamp > > > > > > on this, I'm inclined to believe *at least* having some kconfig_symb > > > > > > exposed for some modules is better than nothing. Christoph are you > > > > > > totally opposed to this effort until we get a non-reverse engineered > > > > > > effort in place? It just seems like an extraordinary amount of work > > > > > > and I'm not quite sure who's volunteering to do it. > > > > > > > > > > > > Other stakeholders may benefit from at least having some config --> > > > > > > module mapping for now. Not just backports or building slimmer > > > > > > kernels. > > > > > > > > > > Christoph, *poke* > > > > > > > > Yes, I'm still totally opposed to a half-backed hack like this. > > > > > > The solution puts forward a mechanism to add a kconfig_symb where we > > > are 100% certain we have a direct module --> config mapping. > > > > > > This is *currently* determined when the streamline_config.pl finds > > > that an object has only *one* associated config symbol associated. As > > > Cristina noted, of 62 modules on a running system 58 of them ended up > > > getting the kconfig_symb assigned, that is 93.5% of all modules on the > > > system being tested. For the other modules, if they did want this > > > association, we could allow a way for modules to define their own > > > KBUILD_KCONF variable so that this could be considered as well, or > > > they can look at their own kconfig stuff to try to fit the model that > > > does work. To be clear, the heuristics *can* be updated if there is > > > confidence in alternative methods for resolution. But since it is > > > reflective of our current situation, I cannot consider it a hack. > > > > > > This implementation is a reflection of our reality in the kernel, and > > > as has been discussed in this thread, if we want to correct the gaps > > > we need to do a lot of work. And *no one* is working towards these > > > goals. > > > > > > That said, even if you go forward with an intrusive solution like the > > > one you proposed we could still use the same kconfig_symb... > > > > > > So no, I don't see this as a hack. It's a reflection as to our current > > > reality. And I cannot see how the kconfig_symb can lie or be > > > incorrect. So in fact I think that pushing this forward also makes the > > > problem statement clearer for the future of what semantics needs to be > > > addressed, and helps us even annotate the problematic areas of the > > > kernel. > > > > > > What negative aspects do you see with this being merged in practice? > > > > I'm trying to see what the actual problem that you are wanting to solve > > here with this. What exactly is it? > > The problem is that there is no current maping of a module to respective > kconfig symbol. That's because it is not just "one" symbol per module. If it were, you can just parse the Makefiles and get that single config option for most modules, right? But even then, multiple options can influence a single module as to what actually gets built into that module. So, I would say, "who really cares"? > > Who needs to determine the > > "singular" configuration option that caused a kernel module to be built > > at the expense of all other options? > > Folks wanting to slim down their kernel build, and users of backports. People who want to "slim" down things are rare, and it's usually worth it to work backwards anyway (see what functionality is needed and then go from there, not look at the modules themselves). Or use a tool like 'make localmodconfig' and trim. > > What can that be used for and who will use it? > > Without a mapping there is no clean way to let you slim down your kernel > using a distro kernel as a base, enabling only those things you really > need. It's hard to determine "what you really need" :) Use localmodconfig and you have a great start, then prune from there. Trying to put _all_ configuration dependencies in a single module isn't going to work, our configuration language does not distill down to that. thanks, greg k-h