Possible to get different object files from the same source code & toolchain?

[josaiah]

Dear all,
I am new to linux programming and I am trying to learn. I have a uClinux kernel that I downloaded and I am trying to compile it. Apparantly, even though a partner and I use exactly the same cross compiling toolchain and source code, we got object files of differing sizes. We have also specified the exact same target architecture (because we use the exact same makefiles and choose exactly the same options). How is it that we can get object files of different sizes?

The only difference is in the version of distro for compilation. He used RedHat 7.3 while I used Redhat 7.1 for compiling. Also, what makes it more perplexing is that both our compiled code works! Which is worrying since I have no way then to verify if both of our compiled code works EXACTLY the same way... The linux.bin file that we generated differed by 8,192 bytes exactly.

Any advice?

Regards,
Josaiah

[Aaron_Adams]

Are you sure the compilers are the exact same version?

If the systems do not have identical processors, it may just be the result of slight differences needed for optimization, etc. I've seen lots of differences in optimization between differing processors of the same architecture.

Typically all compiled code will differ on each individual machine. The only way to assure that it will be identical, is for both systems to install a precompiled ojbect onto their systems.

What is the issue exactly? Is there some reason why you need both objects to be the same size?

[JimH]

The reason you are seeing the difference is probably because of the different versions of glibc that RH 7.1 and RH 7.3 use.

Jim H

[josaiah]

Dear Aaron and Jim,
Thank you so much for the replies. Jim, I will check out the part on the glibc. Anyway, Aaron, I am sure i'm using the exact same version of compiler because I used only what my partner sent me. I wanted them to be the exact same size (and same in content) because I couldn't think of any other way to be assured that our results were the same. I didn't think that the difference in processors should affect the compilation because the target architecture is the same, i.e. I meant for the compiled code to run on an ARM processor and not on my own processor (that compiled the code). Thank you for your help and helpfulness guys! ;D

Regards,
Josaiah