[vox-tech] Relocation errors and dynamic symbols

[Ken Herron]

Peter Jay Salzman wrote:

>"U" doesn't mean a fatal undefined error; it simply means something that
>needs to be linked on the fly by ld.so.  Right?  Is there a way of querying
>ld.so about whether it "knows" a particular symbol?
>  
>
The dynamic linker doesn't know about particular symbols. The nm 
executable contains a list of shared libraries that it was linked with; 
you can use ldd to see this list. When nm is executed, the dynamic 
linker loads those libraries into its address space and tries to resolve 
all of the undefined symbols.

The dynamic linker also has an API which can be invoked to access other 
libraries under the program's control. This is used by things like PAM 
to load authentication modules, or by mozilla to load plugins.