Re: Motivation for -rpath-link

[Nick Clifton <nickc at redhat dot com>]

Hi Volodya,

>> The behaviour is desired because the executable that is being created
>> is supposed to be able to run without requiring *any* shared
>> libraries.  ie it is completely self-contained.
>
> Thanks for the explanation! However, I still don't understand something. Is
> "non-shared non-relocatable link" the same as linking of an excutable, as 
> opposed to .so?

Yes.  Well almost.  Strictly speaking a "non-shared, non-relocatable"
linker output file is a static executable (ie self-contained), which
does not contain any relocation information and so cannot be altered
by a run-time loader to execute at an arbitrary start address.

> In my case, the excutable is regular dynamically linked one, so
> grabbing of transitive dependencies is not required. However, ld
> still tries to do that, and produces the following warning:
>
> /usr/bin/ld: warning: a.so, needed by b/bin/gcc/debug/b.so, not found (try 
> using -rpath or -rpath-link)
>
> Of course, after I copy executable and all libraries to one
> location, all dynamic libraries are found -- so I don't understand
> why 'a.so' is included in link, and what the warning tries to tell
> me.

Which version of the sources are you using ?  This problem was
addressed in a recent series of patches that have been applied to the
sources in the master CVS repository, but which have not yet made it
into an official release.  So if you are not using the CVS sources I
would suggest downloading a snapshot and building yourself a new
linker.

The point of the warning message is that the linker is attempting to
be thorough.  Is sees that b.so needs a.so so it attempts to locate it
and verify that a.so does indeed supply the information needed by
b.so.  Since this is only a warning, it should not stop the linker
from producing an executable, so you can ignore it if you want to.

Cheers
        Nick