Hi Thanks in advance for your help. My apps run in 32-bit mode on Linux in a i586 machine (intel arch). I am planning to go from 32-bit processes to 64-bit processes. My gcc version is provided by Wind River Linux and its' version is 4.1.2. I have below questions. Could not get answer in the on line docs I referred to at http://gcc.gnu.org/onlinedocs/gcc/. 1. if there is an option that does error checking, of long to int OR pointer to int assignments only. just want to get porting errors since it will be LP64. 2. I did not find an option in "Intel 386 and AMD x86-64 Options" to specify the size of long to be 4 bytes so that my apps gets compiled as long of 4 bytes than 8 bytes when compile to 64bit. This option seems to be there for MIPS. Is there some thing I am missing. regards Kiran