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SubjectRe: 2.6 bug: kconfig implementation doesn't match the spec
On Fri, Aug 08, 2003 at 05:16:09PM +0200, Roman Zippel wrote:
> Hi,
>
> On Fri, 8 Aug 2003, Adrian Bunk wrote:
>
> > An example:
> >
> > config FOO
> > tristate
> > default m
> >
> > config BAR
> > tristate
> > default y if !FOO
> > default n
> >
> >
> > According to the kconfig spec BAR should be y, but the implementation in
> > 2.6.0-mm5 sets BAR to n.
>
> You probably forgot to set MODULES, tristate behaves like bool in this
> case and FOO becomes 'y' and '!FOO' is 'n'.

No, this is with CONFIG_MODULES=y.

Let me give another example where the kconfig implementation is
completely broken (BTW: again with CONFIG_MODULES=y):

According to your language definition,
m && !m
evaluates to "m" (it sounds a bit strange but follows directly from
rules (5) and (7) together with the interpretation of "m" as 1 as
explained in the section "Menu dependencies" of
Documentation/kbuild/kconfig-language.txt).

Let's take the following Kconfig snippet:

config MOD
tristate
default m

config TEST8
tristate
default MOD && !MOD

config TEST9
tristate
default m && !m

With the explations above it's obvious both TEST8 and TEST9 should be
"m", but the current 2.6 kconfig implementation says:

# CONFIG_TEST8 is not set
CONFIG_TEST9=y


That's not only different from the expected result directly derived from
the language definition, it also gives two completely different results
for the same expression!


> bye, Roman

cu
Adrian

--

"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed

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