Dynamic Symbol-Dependency Binder (DSDB)

Files

dsdb.01_23_06.tar.gz
dsdb.h
dsdb.c
Makefile
LICENSE

What is it?

This is a linux kernel level module that intends to resolve the problem where, when two modules have a symbol dependency on each other but neither module can be instantiate at run-time because the symbol referenced is currently undefined. More explicitly, this happens when:

      Module A defines EXPORT_SYMBOL() on a symbol used by Module B

      and when,

      Module B defines EXPORT_SYMBOL() on a symbol used by Module A

Upon running `insmod module_[a/b].ko` the kernel will come back with an error stating that a required symbol is not defined. The problem is that each module needs the other loaded before it is able to load itself.

The idea behind DSDB is that instead of statically referencing the exported symbol we can get a pointer to the referenced symbol when it becomes available. Again, since the exported symbols will not be statically referenced, both modules (A and B) can be instantiated without requiring that the other is already load.

Notes

• I'm using void pointers to reference the symbol. You should know that in both the C and C++ standard it is illegal to store the reference of a function in a void pointer. Fortuntely, even though this is illegal it will almost always work; just make sure you properly prototype the function(s) you are using.
• As of 01/23/06 I've only had a years worth of experience writing kernel modules. There might be some built-in way to do this already. I searched the kernel mailing-list archives as well as asked around on IRC. So, let me know if you know of a different/better/correct solution.

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