crossgcc: code wont run from ROM.

[Brendan J Simon <Brendan dot Simon at ctam dot com dot au>]

compiler : powerpc-eabi-g++ (egcs-1.1.2)
libc : newlib (newlib-1.8.1 I think)
os : none.
target architecture : powerpc (mpc860)

I have ported some code that was originally written for the DiabData
compiler.  I have managed to load it into RAM on my embedded system
using the SDS SingleStep debugger via the BDM port.  It runs really
well.

I tried programming it into Flash and it aborts.  The __eabi function
which is called from main() never returns.  I have tracked this down to
malloc returning zero.  The backtrace shows the following functions
being called.

main()
__do_global_ctors()
__get_eh_context()
__get_eh_info()
__get_eh_info()
__empty()
malloc()
_malloc_r()

The SDS debugger does not support the gcc debugging formats so I am
debugging the assembler.  This is getting very tedious but it seems that
_malloc_r() is returning zero.  From newlib's _malloc_r code, it seems
that chucksize(top) is zero which is causing the problem.

    /* Try to extend */
    malloc_extend_top(RCALL nb);
    remainder_size = chunksize(top) - nb;
    if (chunksize(top) < nb || remainder_size < (long)MINSIZE)
    {
      MALLOC_UNLOCK;
      return 0; /* propagate failure */
    }


Has anyone got any ideas what the problem is and/or what I can do to fix
the problem.

Thanks,
Brendan Simon.



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