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From: Ingo Molnar <mingo@elte.hu>
To: David Woodhouse <dwmw2@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: Russell King <rmk+lkml@arm.linux.org.uk>
Subject: Re: [patch] MTD: fix DOC2000/2001/2001PLUS build error
Date: Mon, 5 Feb 2007 17:17:44 +0100	[thread overview]
Message-ID: <20070205161744.GA31740@elte.hu> (raw)
In-Reply-To: <20070205161227.GB4563@flint.arm.linux.org.uk>


* Russell King <rmk+lkml@arm.linux.org.uk> wrote:

> On Mon, Feb 05, 2007 at 04:56:27PM +0100, Ingo Molnar wrote:
> > btw., this whole select problem is not limited to Aunt Tillie: in a 
> > couple of cases in the past few months when i saw some weird code in a 
> > driver and tried to enable it i had to search around for many minutes 
> > and enable random options to figure out its config dependencies until i 
> > had the driver truly enabled. (if there's some easy solution to this 
> > then i'm all ears - but i exclude the easiest solution of adding me to 
> > the 'aunt' category ;-) I think that by blaming Aunt Tillie you might be 
> > missing the real problem.
> 
> Adding a 'select' statement might solve that particular problem:
> 
>  "What config symbols do I need to turn on to enable FOO"
> 
> but it creates another problem which is at precisely the same level. 
> IOW:
> 
>  "What config symbols do I need to turn off to disable FOO"
> 
> Both require the use of grep to solve it.  Both are as bad as each 
> other.  'select' only moves the problem - it doesn't actually solve 
> anything.

yes, in the example above i only outlined that the problem is real and 
not limited to Aunt Tillie's.

> The real problem is that "band-aiding" the problem is all too easy, so 
> we just bung a select in.  We're actually storing up bigger problems 
> for the future, making the kernel configuration system more and more 
> complex, sometimes creating circular dependencies through 
> select/depends, basically turning it into something several orders of 
> magnitude worse than the original shell scripts.

circular dependencies are nicely detected, warned about and worked 
around by the Kconfig system. I fixed one such bug recently. I have to 
say the Kconfig code has improved very significantly during the past few 
years and i dont want any of what i'm writing to be understood as a 
criticism. It's more in the direction of: 'ok, things are pretty nice 
and the config tree works currently, now lets make it even cleaner'.

> The only real way I see the problem truely getting solved is if folk 
> start standing up against throwing "select" in so there's some 
> motivation to actually fix the underlying problem.

the solution is i think two-fold and goes along the lines i outlined in 
the previous mail:

 - make dependencies as tree-alike as possible

note that the MTD problem was caused by those drivers not being part of 
a clean tree.

But even with a 100% clean tree structure there's a legitimate desire to 
select modules several layers down from the current 'leaf' nodes of the 
config tree:

 - provide a tool mode (not a Kconfig language feature) to navigate the
   complete tree of features (including currently disabled ones) and
   enable the selection of components (by automatically selecting all
   dependent features).

	Ingo

  reply	other threads:[~2007-02-05 16:21 UTC|newest]

Thread overview: 95+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-04 19:10 Super Kernel Sunday! Linus Torvalds
2007-02-04 19:40 ` Bauke Jan Douma
2007-02-04 21:00   ` Gene Heskett
2007-02-04 21:11   ` Kevin K
2007-02-04 19:56 ` Alessandro Suardi
2007-02-05  8:39 ` Jonathan Sambrook
2007-02-05  8:45 ` [patch] MTD: fix DOC2000/2001/2001PLUS build error Ingo Molnar
2007-02-05 13:06   ` Josh Boyer
2007-02-05 13:34   ` David Woodhouse
2007-02-05 15:56     ` Ingo Molnar
2007-02-05 16:08       ` Arjan van de Ven
2007-02-05 16:12       ` Russell King
2007-02-05 16:17         ` Ingo Molnar [this message]
2007-02-05 16:22       ` David Woodhouse
2007-02-05 16:26         ` Ingo Molnar
2007-02-05 16:31           ` Ingo Molnar
2007-02-05 16:58             ` Linus Torvalds
2007-02-05 17:05               ` Ingo Molnar
2007-02-05 17:08               ` Russell King
2007-02-05 21:15               ` Ingo Oeser
2007-02-06 13:32                 ` Gerhard Mack
2007-02-05 21:17               ` David Woodhouse
2007-02-05 21:28                 ` Linus Torvalds
2007-02-05 21:39                   ` David Woodhouse
2007-02-05 21:49                     ` Linus Torvalds
2007-02-05 21:53                       ` David Woodhouse
2007-02-05 22:21                         ` Linus Torvalds
2007-02-05 22:31                           ` Randy Dunlap
2007-02-05 23:09                             ` Linus Torvalds
2007-02-05 23:21                               ` David Woodhouse
2007-02-05 23:32                                 ` Linus Torvalds
2007-02-06  0:04                                   ` Mark Rustad
2007-02-06 15:55                                     ` Bill Davidsen
2007-02-06 16:20                                       ` Mark Rustad
2007-02-06  9:45                                   ` David Woodhouse
2007-02-06 15:51                                     ` Bill Davidsen
2007-02-06 16:53                                     ` Linus Torvalds
2007-02-06 22:38                                       ` David Woodhouse
2007-02-06 22:39                                         ` Randy Dunlap
2007-02-06 23:11                                           ` Linus Torvalds
2007-02-06 23:15                                             ` Linus Torvalds
2007-02-06 23:18                                             ` David Woodhouse
2007-02-06 23:49                                               ` Linus Torvalds
2007-02-06 22:53                                         ` Linus Torvalds
2007-02-06 23:11                                           ` David Woodhouse
2007-02-06 23:28                                             ` Linus Torvalds
2007-02-06 23:36                                               ` David Woodhouse
2007-02-06 23:41                                                 ` Randy Dunlap
2007-02-06 23:49                                                   ` David Woodhouse
2007-02-06 23:52                                                   ` Robert P. J. Day
2007-02-06 23:55                                                 ` Linus Torvalds
2007-02-07  0:03                                                   ` David Woodhouse
2007-02-07  0:21                                                     ` Linus Torvalds
2007-02-07  0:30                                                       ` Randy Dunlap
2007-02-07  0:37                                                       ` David Woodhouse
2007-02-07  2:09                                                         ` Linus Torvalds
2007-02-07 13:51                                                       ` Sunil Naidu
2007-02-06  1:09                                 ` Theodore Tso
2007-02-06  6:09                                   ` Matt Mackall
2007-02-06 16:04                                     ` Bill Davidsen
2007-02-06 16:41                                       ` Matt Mackall
2007-02-06 18:03                                         ` Bill Davidsen
2007-02-06  0:00                               ` Jeff Garzik
2007-02-06 13:52                               ` Jörn Engel
2007-02-06 15:16                               ` Mark Lord
2007-02-08  8:18                                 ` David Lang
2007-02-08  9:44                                 ` Jörn Engel
2007-02-06 15:41                           ` Bill Davidsen
2007-02-05 22:21                       ` Alan
2007-02-05 22:35                         ` Linus Torvalds
2007-02-05 21:50                 ` Alan
2007-02-05 21:41                   ` David Woodhouse
2007-02-06  5:46                 ` Matt Mackall
2007-02-06 15:34                   ` Paul Mundt
2007-02-06 22:39                   ` Haavard Skinnemoen
2007-02-06 22:51                     ` Linus Torvalds
2007-02-05 16:33           ` David Woodhouse
2007-02-05 16:46           ` Russell King
2007-02-05 16:52             ` Ingo Molnar
2007-02-05 17:04               ` Russell King
2007-02-05 16:32     ` Linus Torvalds
2007-02-05 16:50       ` Russell King
2007-02-05 16:52       ` David Woodhouse
2007-02-05 17:58 ` Super Kernel Sunday! Jan Engelhardt
2007-02-05 18:07   ` Kevin Fox
2007-02-06 19:02   ` Stephen Hemminger
2007-02-05 21:27 ` [2.6.20] Regression in dmfe driver Thomas Bächler
2007-02-06  9:38   ` Thierry Vignaud
2007-02-06 22:40     ` Thomas Bächler
2007-02-27 13:58 ` [PATA] Failed to set xfermode on LITE-ON LTR-48246S Philipp Matthias Hahn
2007-03-05  4:10   ` Tejun Heo
2007-03-05 10:38     ` Philipp Matthias Hahn
2007-03-05 15:46       ` Tejun Heo
2007-03-06  9:23         ` Philipp Matthias Hahn
2007-03-09 12:50           ` Tejun Heo

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