[fpc-devel] arm-embedded apps crash in exception handler initialization because heapmanager is not initialized

[Michael Ring]

That would of course be even better, the compiler could calculate if 
vars+stack+heap fit in the given memory configuration and issue at 
minimum a warning or even better a compile error.

But this is definitely something that is out of my league, Florin, could 
you implement this?

Michael


Am 03.03.13 21:45, schrieb Florian Klämpfl:
 > Am 03.03.2013 21:27, schrieb Michael Ring:
 >> I have created a new patch, this time it uses the values of the two
 >> commandline parameters -Ch and -Cs to set the size of Stack and Heap. I
 >> am not sure if those params were for this use case but in my opinion it
 >> makes sense.
 >>
 >> Florian, could I ask you to apply the patch to trunk if what I am doing
 >> is is ok?
 >
 > It looks reasonable, but after some thinking I came to the conclusion
 > that maybe the heap should be already allocated during linking, i.e. so
 > heapmgr does not need to calculate an _heap_start.
 >
 >>
 >>
 >> Index: rtl/embedded/heapmgr.pp
 >> ===================================================================
 >> --- rtl/embedded/heapmgr.pp    (revision 23681)
 >> +++ rtl/embedded/heapmgr.pp    (working copy)
 >> @@ -34,7 +34,13 @@
 >>
 >>      var
 >>        Blocks: PHeapBlock = nil;
 >> +      _heap_start : pointer;
 >> +      _heapsize: longWord; external name '__heapsize';
 >> +      _stklen: longword; external name '__stklen';
 >> +      _bss_end: record end; external name '_bss_end';
 >> +      _stack_top: record end; external name '_stack_top';
 >>
 >> +
 >>      procedure InternalFreeMem(Addr: Pointer; Size: ptruint); forward;
 >>
 >>      function FindSize(p: pointer): ptruint;
 >> @@ -242,6 +248,11 @@
 >>
 >>  initialization
 >>    SetMemoryManager(MyMemoryManager);
 >> +  _heap_start := @_stack_top - _heapsize - _stklen;
 >> +  // Only initialize Heap when there is enough space available
 >> +  if _heap_start >= @_bss_end then
 >> +    RegisterHeapBlock(_heap_start,_heapsize);
 >> +
 >>  finalization
 >>    //FinalizeHeap;
 >>  end.




Am 03.03.13 12:36, schrieb Michael Ring:
> This helped me to understand another puzzle piece.
>
> Please correct me if I am wrong:
>
> sram - Memory is divided in several areas on arm-embedded:
>
> _data starts at start of sram ($20000000 in my case)
> _edata is end of _data segment ($200009b4)
> _bss_start defines start of static vars ($200009b4)
> _bss_end defines end of static vars ($20000e90)
>
> all memory from here on is used for stack, stack grows from end of 
> avaliable sram ($20010000) downto _bss_end
>
> so what I could do is allocate memory for heap starting at address 
> _bss_end with the size of _heapsize. or, perhaps even better:
>
> I start using memory at address _stack_top - _stklen - _heapsize
>
> Correct ??
>
> Michael
>
> Am 03.03.13 11:14, schrieb Sven Barth:
>> On 03.03.2013 11:04, Michael Ring wrote:
>>> For a little more flexible solution I would like to ask you one more
>>> questions, it may seem dumb to you but I have never been that deep into
>>> a compiler before so I am learning a lot atm.
>>>
>>> I can see that the compiler param -Ch can be used to define the
>>> heapsize, I can also see in the assembler code of my main program that
>>> when I set -Ch I also get a section:
>>>
>>> -Ch2048 results in this:
>>>
>>> .section .data.n___heapsize
>>>          .balign 4
>>> .globl  __heapsize
>>> __heapsize:
>>>          .long   2048
>>>
>>> but I do not seem to be able to access __heapsize in my code, how could
>>> I use this information to make the heapsize configurable?
>>
>> Did you try
>>
>> === code begin ===
>>
>> var
>>   heapsize: LongWord; external name '__heapsize';
>>
>> === code end ===
>>
>> ?
>>
>> Regards,
>> Sven
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