Fwd: configuring memory size

[D. Peter Siddons]

Hi Till,
The bsp is very similar to the uC5282. _M68k_Ramsize is copied from the 
linker value (_Ramsize) in bsp_start() (part of bspstart.c). I could 
easily check for the two possibilities here. Is that early enough?
Pete.

Till Straumann wrote:

> Eric Norum wrote:
>
>>>
>>> Looks like what I suggested won't work.   The linker complains if  
>>> the expressions in the  ORIGIN/LENGTH contain symbols even if those  
>>> symbols have been defined before the assignment.
>>>
>>> I guess that you'll need to have two separate linkcmds files and  
>>> use something like
>>>     -Wl,-TlinkcmdsFor4MFlash
>>> or
>>>     -Wl,-TlinkcmdsFor16MFlash
>>
>>
> A much better solution would be enhancing the BSP so it does
> auto-detection. This has to be performed early enough,though.
>
> If an early detection is too cumbersome, then you can limit
> the initial size to a minimum, let's say 4M and increase the
> size later. In order to make the additional ram available to
> RTEMS (i.e., after the malloc heap/libc have been initialized)
> you have to implement a trivial 'sbrk()'. The only constraint
> is that the 'late ram'-portion of the heap to be added by sbrk()
> must be contiguous to the initial heap.
>
> You can look at powerpc/shared/bspstart which uses the
> two-staged heap approach for different reasons.
>
> HTH
> T.
>
>>>
>>>
>>>>
>>>> Eric Norum wrote:
>>>>
>>>>>> You need to pass the --defsym option to the linker.
>>>>>>
>>>>>> On the compile line, add something like
>>>>>>     -Wl,--defsym,_RamSize=0x10000000
>>>>>>
>>>>>> On Dec 2, 2005, at 10:50 PM, D. Peter Siddons wrote:
>>>>>>
>>>>>>> I have two boards which are identical except for the amounts  
>>>>>>> of  flash and RAM. The linkcmds file has definitions for these   
>>>>>>> parameters like:
>>>>>>> _RamSize = DEFINED(_RamSize) ? _RamSize : 0x7f0000;
>>>>>>>
>>>>>>> so my question is, can I invoke a definition somewhere in the   
>>>>>>> application make process to override the one in linkcmds? If  
>>>>>>> so,  how and/or where?
>>>>>>>
>>>>>>> Pete.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>
>>> -- 
>>> Eric Norum <norume at aps.anl.gov>
>>> Advanced Photon Source
>>> Argonne National Laboratory
>>> (630) 252-4793
>>>
>>>
>>
>
>