Fwd: configuring memory size

[Till Straumann]

Sorry for the urge I feel to repeat myself.
IMO, the whole approach of creating multiple linker scripts and binaries,
one for each memory / board configuration is bad.
A single instance should perform a run-time check and configure the
workspace and heap according to the amount of memory detected.

T.

Ed Sutter wrote:

> Peter,
> If you're looking for alternatives, then I also have a homegrown tool
> that I use for this.  Very trivial, but does what I want, essentially
> replacing a few sed/awk script with something that keeps everything to 
> one
> simple command line.
> The purpose is slightly different than Thomas's, so you'll have several
> options!  The purpose is to maintain the address information for the 
> linker
> file in my makefile as a variable.  Then the variable can be included in
> CFLAGS if needed, along with being used as input to a template that 
> creates
> the final linker command file.
> Anyway, the tool (called vsub) is included in the MicroMonitor source 
> distribution
> at http://www.microcross.com/html/micromonitor.html, or I can just send
> you the source for that alone.
> Lemme know if you want it.
> Ed
>
> Thomas Doerfler wrote:
>
>> Hi,
>>
>> just as an additional idea: Some years ago I used the C preprocessor 
>> to generate linker command files from a template. The benefit was, 
>> that I could have ONE header file defining address/size information 
>> for the C compiler and for the linker.
>>
>> Maybe this would also be convenient for Peter?
>>
>> wkr,
>> Thomas.
>>
>>
>> D. Peter Siddons wrote:
>>
>>> 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
>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>
>>