[U-Boot] Weak symbols: request for comments

[Sebastien Carlier <sebastien.carlier@gmail.com>]

Dear Wolfgang,

On 11/05/2010 01:14 PM, Wolfgang Denk wrote:
>> 1.1) Stop using weak symbols; use pre-initialized function pointers
>>        instead (possibly grouped in a struct, for cleanliness).
>>        This has the benefit of offering a clear interface and being
>>        independent of toolchain details.
>>      
> And where would the "pre-initialized function pointers" come from?
> Without adding a hell of #ifdef's ?
>    

It would not be pretty, and, as pointed out by Joakim Tjernlund, it 
would not work before relocation.

>> 1.2) Use regular (non-weak) extern declarations for overridable stuff;
>>        collect all default weak symbols into a separate library archive,
>>        to be supplied last to the linker.
>>      
> Not realy practicable, as the code is distributed all over the place,
> and should remain where it logically belongs.
>    

Each module could have its own "defaults.c" for overridable 
implementations, and the build system could collect all of these.  It is 
not a pain-free solution.

>> 1.3) Stop using a library archive for the board specific stuff.
>>        Instead, collect and link all the object files to produce the
>>        output binary.  Only Makefile changes are involved, but correct
>>        behavior depends on all boards doing the right thing.
>>      
> Close. I think stop using a library archives and do what Linux does
> instead is the way to go.
>    

Partial linking with ld -r ?  That does seem like a fairly simple change.

Regards,

Sebastien Carlier