Re: [Mesa3d-dev] undefined symbols and silent fallback to swrast

[tom f. <tf...@al...>]

Xavier Chantry <cha...@gm...> writes:
> 14:47 < lb1> the fact is that if you remove a function from mesa .c file,
>              everything will succeed, but the resulting driver will fail to l
> oad
> 14:47 < lb1> because it cannot resolve that symbol
> 14:48 < lb1> not sure why
> 14:48 < lb1> I suppose even for shared libraries gcc/ld should fail on
>              undefined symbols
> 14:48 < lb1> maybe the makefiles disable that checking
> 
> Can anyone shed any light on this, why the driver always succeeds to
> build and link even in the case of undefined symbols ?

That's just the default compiler/linker setup on Linux.  This is in
contrast to, say, OS X, where undefined symbols cause link errors.

You can emulate the above by building with -Wl,--no-undefined (or maybe
-no-undefined, something like that, see ld(1)).

> The second question is why the dlopen errors are not visible by
> default and require LIBGL_DEBUG=verbose to be displayed.
> It does not make sense to always print these errors by default ?

Doesn't effect me personally, but errors coming up on stderr does seem
like reasonable default behavior to me.  Is it actually the case that
these are always errors though (i.e. if a dlopen fails, does a higher
level try loading a different driver which might succeed?)?

-tom