Re: not catching exceptions

[mark <mark@none.com>]

Thanks for the reply.  I did not realize this is a gcc overall question. 
  I'll post there.  Before I do, I'll create a C++ program to make sure 
I get the same result.

I looked at the link you gave and tried rebuilding the cross compiler 
with -enable-sjlj-exceptions.  Unfortunately, on the target (uclibc) I get

# ./testit
./testit: can't resolve symbol '_Unwind_SjLj_Register' in lib './testit.

I have to leave the target environment alone.  My application is not the 
only one that runs in it (although it is the only Ada one).  So, I can't 
really modify uclibc.


On 10/20/2010 04:11 AM, Ludovic Brenta wrote:
> mark wrote on comp.lang.ada:
>> I'm targeting some Ada95 at three different systems.  One is a host
>> system running Linux, Intel based.  Exceptions are caught just fine.
>> Another is a bare board with a PowerPC running Linux.  Exceptions are
>> also trapped fine.  The third is a system running Linux but instead of
>> using glibc it uses uclibc.  Exceptions are not caught.  All I get is an
>> abort message (abort).  The configure information for this one is below-
>>
>>     $ ./powerpc-mpc8248-linux-uclibc-gcc -v
>>     Using built-in specs.
>>     Target: powerpc-mpc8248-linux-uclibc
>>     Configured with: ../../configure --prefix=/opt/atc/cpp_userchain
>>     /ppc8248-linux-toolchain --target=powerpc-mpc8248-linux-uclibc
>>     --with-cpu=603 --host=i686-pc-linux-gnu --build=i686-pc-linux-gnu
>>     --with-sysroot=/opt/atc/cpp_userchain/ppc8248-linux-toolchain/sysroot
>>     --enable-shared --enable-threads=gnat --disable-tls
>>     --disable__cxa_atexit --enable-languages=c,ada
>>      Thread model: gnat
>>      gcc version 4.1.2
>>
>> I've tried this with both --enable-threads (POSIX model) and
>> enable-threads=gnat.  I've tried with --enable__cxa_atexit and
>> --disable__cxa_atexit.  I can't seem to catch exceptions.
>>
>> A simple test program where I just raise and catch an exception gives
>> the same result...abort.  Outside of not being able to catch exceptions,
>> everything else works great (tasking, protected types, etc).
>>
>> Any thoughts on why exceptions are not being trapped on the  would be
>> appreciated.
>>
>> Thanks.
>
> I found this which may help:
>
> http://gcc.gnu.org/ml/gcc/2007-07/msg00290.html
>
> IIUC, you can enable exceptions on uClibc either by configuring the
> cross-compiler to use the setjump/longjump (SJLJ) mechanism or by
> patching uClibc to support zero-cost exceptions (ZCX).  It is possible
> that a newer version of uClibc is available that handles ZCX, possibly
> with some configuration.
>
> If you have more trouble, I suggest you ask on the GCC mailing list as
> your question is quite technical and not specific to Ada (exceptions
> are handled by the GCC back-end which is common to all languages).
>
> --
> Ludovic Brenta.