Re: [PATCH RFC 1/2] m68k: io_mm.h: conditionalize ISA address translation on Atari

[Michael Schmitz <schmitzmic@gmail.com>]

Hi Finn,

Am 05.06.2021 um 11:31 schrieb Finn Thain:
>>>> If we have Kconfig symbols for 'single platform only', and
>>>> 'multi-platform ISA use', that might be shorter to write and easier
>>>> to understand. Geert?
>>>
>>> It would be nice to have that automatically, like with the current
>>> MULTI_ISA define (and all the MACH_* in
>>> arch/m68k/include/asm/setup.h). Perhaps we should extend kconfig
>>> syntax to define a group of related symbols, and to automatically
>>> generate CONFIG_FOO_MULTI or CONFIG_FOO_SINGLE (and even
>>> CONFIG_BAR_ONLY?) symbols?
>>
>> I take it this is not supported by our current Kconfig syntax?
>>
>
> That may be because CPP hacking is seen as a competitive sport in some
> circles.

Good one.

>
>>> group ISA
>>>      item ATARI_ROM_ISA
>>>      item AMIGA_PCMCIA
>>>      item Q40
>>>
>>> => CONFIG_ISA_MULTI or CONFIG_ISA_SINGLE (+ e.g. ATARI_ROM_ISA_ONLY
>>>    if appropriate).
>>>
>
> Since the items may be bools or tristates, it not clear what type the
> group has.

All three are of type bool.

>
> Anyway, I see that we can already write this:
>
> #define IS_MULTI(a,b) __or(IS_ENABLED(a), IS_ENABLED(b))
>
> So maybe we just need an exclusive-OR macro to go with the other operators
> defined in include/linux/kconfig.h? Then we could write this:
>
> #define IS_SINGLE(a,b) __xor(IS_ENABLED(a), IS_ENABLED(b))
>
> But these only work for a 2-way group. Extending them to N-way groups is
> beyond my CPP abilities. It probably requires N-way __or() and __xor()...

I'll pass on this one for now ...

Cheers,

	Michael