[gentoo-user] Still not feeling familiar with emerge

Dear group,

I'm using gentoo for more than three years now and using the gentoo packaging system
in general is exactly what I expect from a packaging system. You just open a shell
somewhere on your virtual desktop, start a process and the rest is done automatically
(in general).

But, when it comes to packages blocking each other I simply have to guess, what to do next
and sometimes I fail in guessing the right things I once removed the wrong package,
which left me with a system without working packaging system - a very bad experience. In fact
I could only solve this problem by copying a dynamic library from another linux installation
to reanimate emerge.

So some weeks ago I was too busy to take care of some conflicts caused by the end of support
for KDE 3.5). I stopped updating, because I didn't have the time to switch to newer KDE
version and wanted to do that later on.

Now I want to upgrade, but I would like to better understand the messages telling me the
conflicting packets. A current call to 'emerge --update --deep --ask world' gives me the
following conflicts:


 * Error: The above package list contains packages which cannot be
 * installed at the same time on the same system.

  ('installed', '/', 'sys-fs/device-mapper-1.02.24-r1', 'nomerge') pulled in by
    >=sys-fs/device-mapper-1.00.07-r1 required by ('installed', '/', 'sys-fs/cryptsetup-1.0.6-r2', 'nomerge')

  ('ebuild', '/', 'kde-base/kdebase-data-4.3.3', 'merge') pulled in by
    >=kde-base/kdebase-data-4.3.3[-kdeprefix] required by ('ebuild', '/', 'kde-base/kdelibs-4.3.3-r1', 'merge')
    >=kde-base/kdebase-data-4.3.3[-kdeprefix] required by ('ebuild', '/', 'kde-base/kdebase-meta-4.3.3', 'merge')

  ('installed', '/', 'app-arch/lzma-utils-4.32.7', 'nomerge') pulled in by
    app-arch/lzma-utils required by ('ebuild', '/', 'dev-libs/mpfr-2.4.1_p5', 'merge')
    app-arch/lzma-utils required by ('ebuild', '/', 'dev-texlive/texlive-basic-2008-r1', 'merge')
    app-arch/lzma-utils required by ('ebuild', '/', 'dev-texlive/texlive-latex-2008-r2', 'merge')
    (and 5 more)

  ('installed', '/', 'kde-base/akregator-3.5.10', 'nomerge') pulled in by
    >=kde-base/akregator-3.5.10:3.5 required by ('installed', '/', 'kde-base/konqueror-akregator-3.5.10', 'nomerge')

  ('ebuild', '/', 'sys-fs/udev-146-r1', 'merge') pulled in by
    virtual/dev-manager required by world
    >=sys-fs/udev-103 required by ('ebuild', '/', 'media-gfx/iscan-2.21.0', 'merge')
    >=sys-fs/udev-124 required by ('installed', '/', 'sys-fs/cryptsetup-1.0.6-r2', 'nomerge')
    (and 3 more)

  ('ebuild', '/', 'net-wireless/bluez-4.39-r2', 'merge') pulled in by
    net-wireless/bluez required by ('ebuild', '/', 'gnome-base/gvfs-1.2.3', 'merge')
    net-wireless/bluez required by ('ebuild', '/', 'kde-base/solid-4.3.3', 'merge')

  ('ebuild', '/', 'kde-base/akregator-4.3.3', 'merge') pulled in by
    >=kde-base/akregator-4.3.3[-kdeprefix] required by ('ebuild', '/', 'kde-base/kdepim-meta-4.3.3', 'merge')

  ('ebuild', '/', 'app-arch/xz-utils-4.999.9_beta', 'merge') pulled in by
    app-arch/xz-utils required by ('ebuild', '/', 'app-arch/libarchive-2.7.1-r1', 'merge')

  ('installed', '/', 'net-wireless/bluez-libs-3.36', 'nomerge') pulled in by
    net-wireless/bluez-libs required by ('installed', '/', 'net-libs/libpcap-1.0.0-r2', 'nomerge')

  ('installed', '/', 'kde-base/kdebase-data-3.5.10', 'nomerge') pulled in by
    >=kde-base/kdebase-data-3.5.10:3.5 required by ('installed', '/', 'kde-base/kcontrol-3.5.10', 'nomerge')
    >=kde-base/kdebase-data-3.5.10:3.5 required by ('installed', '/', 'kde-base/kicker-3.5.10-r1', 'nomerge')


For me some of the messages are mysterious. What is e.g. the exact meaning of
the four components in
 ('ebuild', '/', 'net-wireless/bluez-4.39-r2', 'merge') or
 ('installed', '/', 'kde-base/akregator-3.5.10', 'nomerge')

How should I resolve the conflict
  net-libs/libpcap-1.0.0-r2 versus gnome-base/gvfs-1.2.3 and kde-base/solid-4.3.3
I don't even have any bluetooth device in my computer. Should I fiddle with the USE flags of
KDE and Gnome or libpcap to avoid they pull in net-wireless/bluez?

Which packets are causing the device-mapper conflict?

What is the most secure way to switch to KDE 4? Should I remove the packages konqueror-akregator,
kcontrol and kicker, then update to KDE 4 and then reinstall those packets?

Maybe someone can explain how to proceed best. Are there some things I can check using
equery or whatsoever to support my decisions? I'm feeling unsure how to handle these
problems keeping the risk to leave my system (partially) unusable as small as possible.
Maybe someone can give me a hint, where to find more information about how to handle conflicts
in the packaging system.

Sorry for the long mail.

Cheers, Heinz