Multilib question

[Michael Eager]

Ian Lance Taylor wrote:
> Michael Eager <eager@eagercon.com> writes:
> 
>> Ian Lance Taylor wrote:
>>> Michael Eager <eager@eagercon.com> writes:
>>>
>>>> I want a multilib configurations to specify two options,
>>>> not just a single option.  I don't see anything in the
>>>> docs which describes how to do this or any target which
>>>> does this.
>>>>
>>>> Is there a way to specify that the 'foo' multilib
>>>> config should be built with -mfoo and -mbar?
>>> You can probably do this but it's not clear what you want.  Multilibs
>>> go two ways: they tell the build process which libraries to build at
>>> build time, and they tell the compiler driver which libraries to link
>>> against at link time.  What should happen if somebody links using just
>>> -mfoo or just -mbar?
>> -mbar is an optimization which is only valid if -mfoo is also specified.
>> Linking a non- -mbar lib with -mfoo works OK, -mbar with non- -mfoo fails.
> 
> In that case, I think one way would be something like
>   MULTILIB_OPTIONS = mfoo mbar
>   MULTILIB_EXCLUSIONS = !mfoo/mbar
> 
> This is not that great, though, in that will build the -mbar library,
> it just won't use it.  I don't know of a way to do exactly what you
> want.

Yeah, that's not quite what I want.  I want the driver to
link in the mbar library if -mbar is specified.

I might (reluctantly) look at how MULTILIB_OPTIONS is
parsed and see if I can make it accept something like

MULTILIB_OPTIONS = mfoo mbar{mfoo}

where this means to generate mbar but also pass -mfoo.

-- 
Michael Eager	 eager@eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077