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From: Luis Chamberlain <mcgrof@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Brendan Higgins <brendanhiggins@google.com>,
	Cristina Moraru <cristina.moraru09@gmail.com>,
	"vegard.nossum@gmail.com" <vegard.nossum@gmail.com>,
	Valentin Rothberg <valentinrothberg@gmail.com>,
	Hannes Reinecke <hare@suse.de>, Sam Ravnborg <sam@ravnborg.org>,
	Michal Marek <mmarek@suse.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Tom Gundersen <teg@jklm.no>, Kay Sievers <kay@vrfy.org>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Andrew Morton <akpm@linux-foundation.org>,
	backports@vger.kernel.org, Guenter Roeck <linux@roeck-us.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"rafael.j.wysocki" <rafael.j.wysocki@intel.com>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Takashi Iwai <tiwai@suse.de>,
	Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	Hauke Mehrtens <hauke@hauke-m.de>,
	Paul Bolle <pebolle@tiscali.nl>,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Alexey Khoroshilov <khoroshilov@ispras.ru>,
	Sathya Prakash Veerichetty <sathya.prakash@broadcom.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Laurence Oberman <loberman@redhat.com>,
	Johannes Thumshirn <jthumshirn@suse.de>,
	Tejun Heo <tj@kernel.org>,
	Jej B <James.Bottomley@hansenpartnership.com>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Daniel Jonsson <danijons@student.chalmers.se>,
	Andrzej Wasowski <wasowski@itu.dk>
Subject: Re: [RFC PATCH 0/5] Add CONFIG symbol as module attribute
Date: Fri, 28 Jun 2019 11:40:22 -0700
Message-ID: <CAB=NE6Xa525g+3oWROjCyDT3eD0sw-6O+7o97HGX8zORJfYw4w@mail.gmail.com> (raw)
In-Reply-To: <20190627045052.GA7594@lst.de>

On Wed, Jun 26, 2019 at 9:51 PM Christoph Hellwig <hch@lst.de> 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 <mcgrof@kernel.org> 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?

 Luis
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Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1471462023-119645-1-git-send-email-cristina.moraru09@gmail.com>
2016-08-18 17:55 ` Luis R. Rodriguez
2016-08-19  9:07   ` Michal Marek
2016-08-22 19:48     ` Cristina-Gabriela Moraru
2016-08-23 21:32     ` Luis R. Rodriguez
2016-08-24 11:05       ` Michal Marek
2016-08-24 16:33         ` Luis R. Rodriguez
2016-08-24 17:31           ` Naveen Kumar
2016-08-22 19:35   ` Cristina-Gabriela Moraru
2016-08-23 19:17     ` Luis R. Rodriguez
2016-08-25  7:43   ` Christoph Hellwig
2016-08-25  8:00     ` Johannes Berg
2016-08-25 19:51       ` Luis R. Rodriguez
2016-08-25  8:41     ` Michal Marek
2016-08-25 20:19     ` Luis R. Rodriguez
2019-02-05 22:07       ` Luis Chamberlain
2019-06-26 22:21         ` Luis Chamberlain
2019-06-27  4:50           ` Christoph Hellwig
2019-06-28 18:40             ` Luis Chamberlain [this message]
2019-06-29  8:42               ` Greg Kroah-Hartman
2019-07-02 20:51                 ` Luis Chamberlain
2019-07-03  7:40                   ` Greg Kroah-Hartman
2019-07-03 16:50                     ` Luis Chamberlain
2019-07-03 18:57                       ` Greg Kroah-Hartman
2019-07-03 22:25                         ` Luis Chamberlain
2019-07-11 23:07                           ` Brendan Higgins
2019-07-11 23:22                             ` Luis Chamberlain
2019-07-03 12:16               ` Enrico Weigelt, metux IT consult
2019-07-03 17:35                 ` Luis Chamberlain
2019-07-03 19:31                   ` Enrico Weigelt, metux IT consult
2019-07-03 22:42                     ` Luis Chamberlain
2019-07-11 23:27                       ` Brendan Higgins
2019-07-13 14:44                         ` Enrico Weigelt, metux IT consult
     [not found] ` <1471462023-119645-3-git-send-email-cristina.moraru09@gmail.com>
2016-08-18 18:10   ` [RFC PATCH 2/5] Add CONFIG symbol to module as compilation parameter Luis R. Rodriguez
2016-08-18 18:55     ` Luis R. Rodriguez
2016-08-20 15:11     ` Cristina-Gabriela Moraru
2016-08-23 19:07       ` Luis R. Rodriguez
     [not found] ` <1471462023-119645-2-git-send-email-cristina.moraru09@gmail.com>
2016-08-18 18:22   ` [RFC PATCH 1/5] Add generation of Module.symb in streamline_config Luis R. Rodriguez
2016-08-18 18:32     ` Luis R. Rodriguez
     [not found]     ` <CAGZ2q2xi9Uy-ye387=mWhy_fOEJBC593Nos7fH027m-_ZdoOXA@mail.gmail.com>
2016-08-20 14:49       ` Cristina-Gabriela Moraru
2016-08-23 19:00       ` Luis R. Rodriguez
     [not found] ` <1471462023-119645-4-git-send-email-cristina.moraru09@gmail.com>
2016-08-18 18:30   ` [RFC PATCH 3/5] Trigger Module.ksymb generation in Makefile Luis R. Rodriguez
     [not found] ` <1471462023-119645-5-git-send-email-cristina.moraru09@gmail.com>
2016-08-18 18:59   ` [RFC PATCH 4/5] Set KCONFIG_KSYMB as value for kconfig_ksymb module attribute Luis R. Rodriguez
2016-08-20 15:16     ` Cristina-Gabriela Moraru
2016-08-23 19:10       ` Luis R. Rodriguez
     [not found] ` <1471462023-119645-6-git-send-email-cristina.moraru09@gmail.com>
2016-08-18 19:02   ` [RFC PATCH 5/5] Add kconf_symb as kernel " Luis R. Rodriguez

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