Ideally, all libraries should report zero unused direct dependencies
when inspected with ldd -r -u. Although in some sense unused libraries
are harmless, they do put needless pressure on the kernel's VM since all
processes linked with the affected libraries have to map many more
files, and in principle you can get unexpected behaviour when symbols
don't resolve the way you expect due to namespace collisions.
Several of the core X libraries fail this, for not particularly good
reasons. I've fixed most of them by now, but there's one or two
stragglers still.
The side effect of this is that the culled libraries will not be
included in the linker search scope for any libraries or applications
above them in the stack. For example, libXaw no longer links against
libSM, so if your application linked against libXaw and not libSM, but
used symbols from libSM, it may now fail at runtime claiming that some
symbols could not be resolved. If this happens, the affected package
needs to be fixed to link against all appropriate libraries directly.
I doubt anyone will actually run into that, but I wanted to give a heads
up in case it does happen.
(Ideally we should be able to do this for the entire OS. Baby steps.)
- ajax
