Global data loaded if symbols aren't resolved

[Marcus Clyne]

Ian Lance Taylor wrote:
> Marcus Clyne <maccaday@gmail.com> writes:
>
>   
>> If a shared object is loaded using dlopen etc and the symbols in its
>> object aren't used (specifically they are defined elsewhere already
>> inside that process), is the data in the symbols automatically loaded
>> into memory or is it skipped (assuming there are no other programs
>> using those symbols on the system) and the memory available for other
>> purposes?
>>     
>
> If you open a shared library with dlopen, then that library is loaded
> into memory.  This will use up virtual address space.  If you don't use
> the library for anything, then the pages will never be loaded into RAM.
>   
When the object loaded initially with dlopen(), is there anything that's 
transferred to RAM (e.g. the page where the symbol names are), or are 
they only copied to the swap space directly?  If that's the case, are 
they then loaded into RAM when dlsym() is called?

Thanks,

Marcus.