libc-2.3.3 and gcc-3.4.3 cross compiler

Feb 07, 2006 1 Replies
U

We are running embedded linux-2.4.21 on an ARM9 processor (Cirrus Logic with MaverickCrunch math coprocessor) and I have successfully cross-compiled a gnu toolchain on Windows (cygwin), Linux, and Solaris 2.8 (sparc). I am able to cross-build binaries on all platforms and run them on the ARM9 so it looks as if everything is running fine.



My question is that the (glibc) libc-2.3.3.so that was built on Windows and Solaris is a different size from the one built on Linux and the one that is actually residing on the ARM9 board. I listed the maps (arm-linux-nm and sort) and notice that the function offsets are slightly different. For example:



Window and Solaris libc-2.3.3.so:


0002e360 T atof
0002e37c T atoi
0002e39c T atol
0002e3bc T atoll

ARM9 libc-2.3.3.so:


0002e2e0 T atof
0002e2fc T atoi
0002e31c T atol
0002e33c T atoll

Will this cause problems or not? So far my programs seem to run fine but I am a little concerned by this. Should I be using exactly the same libc in the cross-compile environement as the running environment?



Thanks,



Snake


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U

To answer my own question, (from:

formatting link

The magic trick here that makes it work is a chunk of data called a Procedure Linkage Table (PLT), a table in the program that lists every function that a program calls. When the program is started, the PLT contains code for each function to query the runtime linker for the address at which it has loaded a function. It then fills in that entry in the table and jumps there. As each function is called, its entry in the PLT is simplified into a direct jump to the loaded function.

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