On Sun, May 20, 2007 at 05:25:24AM +0530, Satyam Sharma wrote:
> On 5/20/07, Adrian Bunk <bunk@xxxxxxxxx> wrote:
>> On Sun, May 20, 2007 at 05:06:33AM +0530, Satyam Sharma wrote:
>> > On 5/20/07, Adrian Bunk <bunk@xxxxxxxxx> wrote:
>> >>...
>> >> Consider ATARI_KBD_CORE was used by 20 drivers.
>> >>
>> >> Using select for such not user visible helper variables is a really
>> nice
>> >> thing, and much more readable (and therefore much less likely to
>> contain
>> >> bugs) than dependencies with tons of "||"'s.
>> >
>> > Well, the "default .. if .." kind of idiom is fairly common (I could say
>> > almost standard), in arch/.../config's. It's been used for some time,
>> > and for several symbols over there. But you're right that if 20 drivers
>> > used ATARI_KBD_CORE, we'd get tons of ugly "||"'s there, so
>> > perhaps we do need some kind of fix for this.
>>
>> And the fix is to use select.
>>
>> Compare the handling of options like IRQ_CPU in arch/mips/Kconfig in
>> current kernels with the handling in kernel 2.6.0 .
>>
>> Or as an exercise, change drivers/net/Kconfig to no longer use
>> "select MII". When you are finished, ensure that you are handling it
>> properly although the option is user visible...
>
> "config MII" and "select MII" are _not_ equivalent to the case at hand.
> MII is defined in drivers/net/Kconfig itself so does not print any "symbol
> unknown kind of warnings" ... so clearly no probs in "select" for it ...
Then move the "config MII" to arch/i386/Kconfig and assume all drivers
select'ing it would depend on X86_32.
>> There are cases where "default .. if .." is the right idiom, but there
>> are also cases where "select" is the right idiom. And for helper code
>> like ATARI_KBD_CORE, "select" is the right idiom.
>
> ATARI_KBD_CORE, unlike MII, is defined only by some archs. And the
> correct (most widely used or standard, in any case) idiom for that is
> "default .. if ..". Or perhaps you can convert those helper code options in
> arch/.../config's over to select too, as an exercise? :-)
Perhaps not as an exercise, but actually for real.
We had "fixed" such warnings in the past similar to your patch, but that
was actually a mistake.
And "correct" can easily be the opposite of "most widely used or standard"
if you discover that you did it wrong in the past.