cross-compiling LM32 internal error while linking

[Federico Vaga]

Following another way to get the same error message.
In this case it is enough to remove the line 'memset(&a, 0, sizeof(a));'
to make the error disappear.

-------------------------------------
#include <string.h>
#include <stdlib.h>

struct test {
	int a;
	int b;
	int c;
};

int main(int argc, char *argv[])
{
	struct test a;
	int b;

	memset(&a, 0, sizeof(a));
	memset(&b, 0, sizeof(b));

	return 0;
}
-------------------------------------

Do you need also my linker script file?


On Fri, Feb 05, 2016 at 03:58:05PM +0100, Federico Vaga wrote:
>I think I got the source of the problem. I was writing the
>simple testcase that you asked me:
>
>
>#include <stdlib.h>
>
>int main(int argc, char *argv[])
>{
>	exit(0);
>}
>
>
>/bin/lm32-elf-gcc -c -o wrn-crt0.o wrn-crt0.S
>/bin/lm32-elf-gcc -c -o rt-mturtle.o rt-mturtle.c
>/bin/lm32-elf-gcc -c -o gcclm32-bug.o gcclm32-bug.c
>/bin/lm32-elf-gcc -o gcclm32-bug.elf -nostartfiles wrn-crt0.o rt-mturtle.o gcclm32-bug.o -T wrnode.ld -lgcc -lc
>/lib/gcc/lm32-elf/5.3.0/../../../../lm32-elf/bin/ld: internal error: addend should be zero for R_LM32_16_GOT
>/lib/gcc/lm32-elf/5.3.0/../../../../lm32-elf/bin/ld: internal error: addend should be zero for R_LM32_16_GOT
>
>
>
>In the file rt-mturtle.c I have my syscall stubs in order to avoid errors like:
>
>newlib-2.2.0-1/newlib/libc/stdlib/exit.c:70: undefined reference to `_exit'
>
>
>
>The problem is with the errno 'variable'. According to:
>
>https://sourceware.org/newlib/libc.html#Stubs
>
>for function like fork(), I followed the example:
>
>#include <errno.h>
>#undef errno
>extern int errno;
>int fork(void) {
> errno = EAGAIN;
> return -1;
>}
>
>
>
>The errno trick of undefining the macro and set the an external variable causes
>the error:
>
>/lib/gcc/lm32-elf/5.3.0/../../../../lm32-elf/bin/ld: internal error: addend should be zero for R_LM32_16_GOT
>
>
>Of course. Now I'm able to compile without errors if I avoid to use errno. But
>I do not thing is the right(tm) solution.
>
>On Fri, Feb 05, 2016 at 11:23:53AM +0000, Nick Clifton wrote:
>>Hi Federico,
>>
>>>When I compile my code I get this message:
>>>
>>>ld: internal error: addend should be zero for R_LM32_16_GOT
>>>
>>>Then the compilation complete without errors (O_O)
>>>(like if that error is not an error but a warning)
>>
>>This is a bug.  Either the code being linked is broken somehow, possibly
>>due to a compiler or assembler error, and so the link should not have
>>succeeded.  Or else the error message is actually a warning about behaviour
>>that the programmer (of the linker) was not expecting, and so the linker
>>might not have behaved correctly.
>>
>>A simple testcase to reproduce the problem would certainly be helpful for
>>whomever does investigate this problem.
>>
>>
>>>I do not understand what does this mean, and I cannot find information on
>>>the web. Any hint?
>>
>>Well the error message comes from the lm32_elf_relocate_section function in the
>>bfd/elf32-lm32.c source file, where it is processing the R_LM32_16_GOT reloc.
>>
>>Exactly what this relocation is supposed to do and why its addend should be zero
>>I do not know.  It is presumably specified by the ABI for the LM32 architecture,
>>but I could not find a copy of this document on the web. :-(
>>
>>
>>>If this is not the right place, can you redirect me to the
>>>right place?
>>
>>Probably the best person to ask would be the maintainer for the LM32 code -
>>Jon Beniston.  I have added him to the CC list of this email.
>>
>>Cheers
>> Nick