linux-kernel - Re: kbuild: fixing the select problem

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Date:	Thu, 6 May 2010 15:36:31 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	James Bottomley <James.Bottomley@...senpartnership.com>
Cc:	linux-arch@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Sam Ravnborg <sam@...nborg.org>, linux-kbuild@...r.kernel.org,
	Randy Dunlap <randy.dunlap@...cle.com>
Subject: Re: kbuild: fixing the select problem

On Thu, May 6, 2010 at 15:17, James Bottomley
<James.Bottomley@...senpartnership.com> wrote:
> On Thu, 2010-05-06 at 08:47 +0200, Geert Uytterhoeven wrote:
>> On Wed, May 5, 2010 at 23:49, James Bottomley
>> <James.Bottomley@...senpartnership.com> wrote:
>> > [Sam: I know you don't maintain kbuild anymore, but since you have the
>> > most experience, if you could find time to comment, I'd be grateful]
>> >
>> > The select problem is that the kbuild select directive will turn a
>> > symbol on without reference to its dependencies.  This, in turn, means
>> > that either selected symbols must select their dependencies, or that
>> > people using select have to be aware of the selected symbol's dependency
>> > and build those dependencies into their symbol (leading to duplication
>> > and the possibility of getting the dependencies out of sync).  We use
>> > select for the scsi transport classes, so we run into this problem in
>> > SCSI quite a lot.
>> >
>> > I think the correct fix is to make a symbol that selects another symbol
>> > automatically inherit all of the selected symbol's dependencies.
>>
>> What if there's a good reason the selected symbol has this dependency?
>> E.g. it depends on a critical feature not available? Like CONFIG_HAS_IOMEM?
>
> I don't quite understand the question.  If a selected symbol has a
> critical dependency which is config'd to N then the build usually
> breaks ... that's what I'm calling the select problem.  I thought
> CONFIG_HAS_IOMEM was usually selected by the architecture, though.  In
> the new proposal, we wouldn't be able to generate the invalid
> configuration in the first place.

Sorry, my fault, -EREPLY_TOO_EARLY_AFTER_WAKEUP.
Upon rereading what you actually wrote, it made complete sense, and my
question didn't.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds
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