Re: Compiling for i586 architecture - illegal instruction on executable

[Renato Mendes <renato dot mendes dot pes at gmail dot com>]

Johann:

I  tried to compile and run on gdb and here is what IÂve got:

First IÂve added the -g flag:

g++ -march=i586 test.cpp -g -o test586.cpp -static -static-libgcc
-static-libstdc++

Then on target machine:


[root@DSC_DKLinux:/]$ gdb ./test586


dlopen failed on 'libthread_db.so.1' - /lib/libthread_db.so.1: symbol
__libc_write, version GLIBC_PRIVATE not defined in file libc.so.6 with
link time reference
GDB will not be able to debug pthreads.

GNU gdb 5.3.92
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GDB is free software, covered by the GNU General Public License, and you are
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This GDB was configured as "i586-suse-linux"...Dwarf Error: wrong
version in compilation unit header (is 4, should be 2) [in module
/test586]

(gdb) run


Here the run get stuck - nothing happens and I have to abort using CTRL-Z

BTW: IÂve tried both march=i586 and march=i486


Florian:

So, for Ubuntu I would need to download the gcc latest source code and
recompile it or is there a shorter way to go ? What flags would that
be used for compilation ?

Abount Debian, you mean that if I switch my developmnet machine to
Debian and install the latest gcc it will generate usable code for my
Vortex processor using the -march=i586 flag ?




2015-09-27 11:16 GMT-03:00 Johann Klammer <klammerj@a1.net>:
> On 09/27/2015 03:36 PM, Renato Mendes wrote:
>> I have Ubuntu 12.01 with gcc 4.8.2 as a host and I need to do a cross
>> compilation for a Vortex86DX CPU embedded system running an old 2.6.23
>> kernel. Although I had succeeded installing a newer 4.7.4 gcc in
>> Vortex (from previous post), due to the lack or resources I need to be
>> able to cross compile for the Vortex architectue using my Ubuntu host.
>>
>> IÂm trying the following testing code:
>>
>>     #include <iostream>
>>
>>     int main()
>>     {
>>        std::cout << "Hello world" << std::endl;
>>     }
>>
>> That is compiled using the following command line:
>>
>>     g++ -march=i586 test.cpp -o test586.cpp -static -static-libgcc
>> -static-libstdc++
>>
>> When I run the test586 on the target architecture IÂm getting this error:
>>
>>     $ ./test586
>>     Illegal instruction
>>
>> Browsing on the internet it seens that I need to "build the whole
>> toolchain for 586" on Ubuntu, but IÂm really confused about how to do
>> it... Shall I need to install something ?
>>
>> Is the -march=i586 parameter the only thing needed ? IsnÂt it logical
>> to gcc to choose the correct 586 libraries in that case ?
>> Does that Illegal instruction problem come from libraries that is
>> linked using a 686 architecture ?
>> How can I tell the compiler to use the 585 libraries ?
>>
>>
>> IÂm really very confused on how to solve this issue and help is very
>> much appreciated. [here][1]
>>
>>
>>   [1]: http://stackoverflow.com/questions/32781281/gcc-cross-compile-to-a-i586-architecture-vortex86dx
>>
> Run it in gdb and do a disassemble after you get the fault.
> Post the results here. Esp. the instructions around the instruction pointer(it's marked in the output).
> I do not know if the dmesg log shows the address of the fault, but if it does,
> you might also be able to get at the faulting instruction with nm.
>
> Background: AFAIK some processors branded as 586 were lacking some 586 instructions.
> You want to know which insn faulted, so you can tell if you have one of those.
>