Axel and Ian, you both are right there are many possibilities. Sorry, I forgot to mention gcc version. It is as below: 32-bit: # gcc -v Using built-in specs. Target: i386-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --disable-plugin --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic --host=i386-redhat-linux Thread model: posix gcc version 4.1.2 20080704 (Red Hat 4.1.2-50) 64-bit: # gcc -v Using built-in specs. Target: x86_64-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --disable-plugin --with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic --host=x86_64-redhat-linux Thread model: posix gcc version 4.1.2 20080704 (Red Hat 4.1.2-50) Crash is a Segmentation fault. Let me get some more information so we can drill down to the issue. Regards, Mitesh Thakkar On Fri, Jul 22, 2011 at 6:52 PM, Ian Lance Taylor <iant@xxxxxxxxxx> wrote: > Mitesh Thakkar <mail.mthakkar@xxxxxxxxx> writes: > >> On Fri, Jul 22, 2011 at 3:09 PM, Mitesh Thakkar <mail.mthakkar@xxxxxxxxx> wrote: >>> Hi All, >>> >>> I have developed one custom application in C. >>> It is running fine in CentOS 5.6 64-bit, but it is crashing in CentOS >>> 5.6 32-bit. >>> I am not finding any reason/conclusion for it. >>> Can anyone help me for it. >> >> Interestingly, it is not crashing on 32-bit if I give -O0 (I mean do >> not optimize). >> What could be the reason. > > I assume you are compiling with the -m32 option to generate 32-bit code. > > You neglected to mention which version of gcc you are using. You > neglected to mention what the crash looks like--e.g., is it a > segmentation violation or an illegal instruction? > > While of course it could be anything at all, the most likely reason is > that your program is invalid C, and that the 32-bit optimizers are > changing it in a way that causes it to not behave as you expect. If the > program works as you expect if you compile with -O2 -fno-strict-aliasing > -fno-strict-overflow then that is almost certainly the problem. > > Ian >