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Forum: ARM programming with GCC/GNU tools linker errors caused by malloc and free


von jrmymllr j. (jrmymllr)


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I'm getting this linker error:

arm-none-eabi/lib/thumb2libc.a(lib_a-sbrkr.o): In function `_sbrk_r':
sbrkr.c:(.text+0xc): undefined reference to `_sbrk'
collect2: ld returned 1 exit status

I think I partly figured out the linker problem. If I remove all
references to malloc and free, the source compiles (CodeSourcery G++).
So, obviously I have a problem with malloc/free. I believe it's using
the compiler's built in functions. So, what do I do? I have no idea
what's missing here. If extra code needs to be written, I'm not sure how
or why. Shouldn't this be taken care of by the compiler?

von Martin T. (mthomas) (Moderator)


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Jerry Milner wrote:
> I'm getting this linker error:
>
> arm-none-eabi/lib/thumb2libc.a(lib_a-sbrkr.o): In function `_sbrk_r':
> sbrkr.c:(.text+0xc): undefined reference to `_sbrk'
> collect2: ld returned 1 exit status
>
> I think I partly figured out the linker problem. If I remove all
> references to malloc and free, the source compiles (CodeSourcery G++).
> So, obviously I have a problem with malloc/free. I believe it's using
> the compiler's built in functions. So, what do I do? I have no idea
> what's missing here. If extra code needs to be written, I'm not sure how
> or why. Shouldn't this be taken care of by the compiler?

Suggestion can be found http://en.mikrocontroller.net/topic/155464#new

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