Bare metal ARM Cross compiler for arm-none-eabi target without libunwind?

[Sebastian Huber]

On 03/28/2012 11:33 AM, Fredrik Hederstierna wrote:
>
>>> We generate the map-file, the content tells that (if I understand correctly)
>>>
>>> "_divdi3.o"  use "__aeabi_unwind_cpp_pr0" which resides in "unwind-arm.o".
>>>
>>> Is it really correct that we need unwind-support if just using division?
>>> Could it be that _divdi3 can 'throw' division-by-zero 'exception' ?
>>> (We have overloaded div0: "void __div0(void) { assert(0); }" so we dont want unwinding here anyway...)
>>
>
>> I suspect (but you'll have to check) that this is because _divdi3 is
>> compiled with exceptions, and this is indeed because division by zero
>> might throw.  The simplest fix is to compile it without exceptions.
>> The correct fix is to make unwinding work on your platform.
>
> Sorry I don't fully agree, we don't want the unwinding stuff.
> We are very short on flash memory, and we do not want to waste bytes on unnecessary code.
>
> Also, why does it work with 'arm-none-elf', shouldn't it be the same regarding __div0?
> The correct solution would be to exclude dependency to unwind from _divdi3 when building a bare metal toolchain.

For me it is also unclear why we need this division by zero exception in the 
bare metal tool chain.  See also:

http://gcc.gnu.org/ml/gcc-help/2011-03/msg00149.html

-- 
Sebastian Huber, embedded brains GmbH

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