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

Albert ARIBAUD
2010-11-19T06:36:05Z

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.