[U-Boot] [PATCH v3] Switch from archive libraries to partial linking

[Albert ARIBAUD <albert.aribaud@free.fr>]

Le 18/11/2010 23:33, Wolfgang Denk a ?crit :
> Dear Albert ARIBAUD,
>
> In message<4CE5A3F1.50304@free.fr>  you wrote:
>>
>>>    58     arch/powerpc/cpu/mpc8xx/start.o             (.text)
>>>    59     arch/powerpc/cpu/mpc8xx/traps.o             (.text)
>>>    60     common/dlmalloc.o           (.text)
>>>    61     arch/powerpc/lib/ppcstring.o                (.text)
>>>    62     lib/vsprintf.o      (.text)
>>>    63     lib/crc32.o         (.text)
>>>    64     lib/zlib.o          (.text)
>>>    65     arch/powerpc/lib/cache.o            (.text)
>>>    66
>>>    67     . = DEFINED(env_offset) ? env_offset : .;
>>>    68     common/env_embedded.o       (.ppcenv)
> ....
>> Are you sure of this? From
>> <http://sourceware.org/binutils/docs-2.20/ld/Input-Section-Basics.html#Input-Section-Basics>,
>> specifying a file name in the linker file *and* on the command line
>> should not lead to a double inclusion of the object file:
>
> I'm sure that I see the errors.
>
> I see two possible reasons: 1) whay you describe is a new feature in
> binutils 2.20; I'm currently using 2.17.50 (with ELDk 4.2); or 2) the
> linker does not realize it because it's actually different file names:
> for example, vsprintf() gets included in the linker script directly
> through lib/vsprintf.o, and throught he command line as
> lib/libgeneric.o ==>  two different file names.

Most probably 2); mentioning a file in the linker script either with or 
without mentioning it on the command line has certainly been done for 
some time, so I doubt the feature is new; and certainly the doc is about 
files, not symbols in different files.

And, to get back to possible solutions, I don't know that the linker can 
map selected symbols onto specific regions; it can only place whole 
object files.

The simplest, though not cleanest, way I can think of is to put 
conditionals to not compile vsprintf() in lib/generic, and set those 
conditions from the board config file -- and same for anything else. 
Ugly, but it will work.

A second solution, a bit more intrusive, would be to split lib/generic 
in two files; a "small" one which could be mapped in the small area, and 
the rest, which would map with the rest of the image.

> Best regards,
>
> Wolfgang Denk
>

Amicalement,
-- 
Albert.