On Thursday 17 June 2010 17:54:35 Alex Schuster wrote:
> Colleen Beamer writes:
> > First, I looked in the archives and didn't find anything relevant -
> > could be my stupidity, but I did try!
> 
> Fine :)
> 
> > From my kdm log the last few lines are as follows:
> >
> > (EE) Failed to load module "dri" (module does not exist, 0)
> > (EE) Failed to load module "dri2" (module does not exist, 0)
> 
> I have this too, when using ati-drivers. I think the nvidia-drivers also
> have their own dri, so this is okay.
> 
> > /usr/lib/kde4/libexec/kdm_greet:  error while loading shared libraries:
> > libpng12.so.0:  cannot open shared object file:  No such file or
> > directory
> 
> [...]
> 
> > Regarding libpng - on my first upgrade 6 days ago, I removed libpng
> > prior to doing the update because the updated libpng file was being
> > blocked by the existing one.  I don't know if this makes a difference.
> 
> This is the problem. /usr/lib/kde4/libexec/kdm_greet links to
> libpng12.so.0, which you removed. It needs to be rebuilt so it links
> against libpng14.so.0. A simple emerge -1 kde-base/kdm should solve this.
> Use ldd /usr/lib/kde4/libexec/kdm_greet to verify this, there should be no
> 'not found' entries.
> 
> Better use revdep-rebuild, there might be many other things that are still
> linked to the old libpng.
> 
> You could also try to emerge media-libs/libpng:1.2, this will install the
> old libpng in parallel. At least I do have both on my system, but my kdm
> inks to 1.4. If the revdep-rebuild list is very long, maybe you can get a
> working system faster this way.

 
media-libs/libpng-1.4.2 is still ~amd64 and ~x86, so there shouldn't be a need 
to emerge it at this stage.  Alex's suggestion to emerge -1aDv kde-base/kdm 
will most likely fix your problem and you can run revdep-rebuild afterwards 
for good measure.
-- 
Regards,
Mick