1

Running a (C)LFS-x86_64 Linux computer with 32 bit libraries installed in parallel in /{usr,}/lib32 (compared with /{usr,}/lib64 which contains the same libraries, plus a couple extra.)

Finished installing a pair of Qt-5.4.0 libraries to /opt/qt5 (symbolic link to /opt/qt-5.4.0/) with a pair of library directories and plugins installed within the arch-specific library dirs.

Now curious as to if it's worth installing 32-bit KDE. In addition to KDE being a pain to find all the bits of anyway, installing a pair of each KDE library (and plausibly executables in some cases) will take more than twice as long.

Edit - Highlighting question below

How many things depend on KDE libs? (Outside of KDE packages)

Am I likely to be caught out if I only install a 64-bit KDE? (w.r.t. closed source programs, eg VirtualBox (shouldn't require KDE libs?), spotify (runs fine on my 'pure' 64-bit system with a couple of static libraries), etc...)

3

If something requires a library that is not present it simply will not work (as in, will not even start). There is no mystery or ambiguity to it. If the applications you mention run, then you are fine.

You can check what libraries a binary needs to link with ldd. For example:

> ldd /opt/VirtualBox/VirtualBox
    linux-vdso.so.1 =>  (0x00007fff02b70000)
    libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f06d744f000)
    libdl.so.2 => /lib64/libdl.so.2 (0x00007f06d724b000)
    libstdc++.so.6 => /lib64/libstdc++.so.6 (0x00007f06d6f42000)
    libc.so.6 => /lib64/libc.so.6 (0x00007f06d6b84000)
    /lib64/ld-linux-x86-64.so.2 (0x00007f06d768e000)
    libm.so.6 => /lib64/libm.so.6 (0x00007f06d687d000)
    libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f06d6666000)

So no, that one does not need 32-bit KDE libs. There are other binaries associated with VirtualBox, I am not sure what they are all for, but they include some libs with Qt in their name, e.g. libQtGuiVBox. But find /opt/VirtualBox -executable -name "*Qt*" ldd '{}' + shows them as all linking to 64-bit libs and again, nothing to do with KDE.

Keep in mind that although KDE uses Qt, Qt is independent of KDE. They are not the same project. Requiring Qt does not mean requiring KDE. I can't see any reason why closed source apps like the ones you mention would require parts of KDE, although more obtuse things happen.

If a binary requires a library that's missing, you'll get, e.g.:

 libQtCoreVBox.so.4 => not found

VirtualBox is a bit of a special case, however; the reason this isn't found by the linker is it isn't in the normal library path. But vbox is actually started with a script that presumably takes care of those details.

  • Well, thank you for the explanation, but I already knew how to find/check library requirements - I suppose my question was not very good. I mean that although many things might link against Qt, and some of them might require a 32-bit Qt (reasonably unlikely, but not so unlikely that I didn't want to install), I couldn't imagine many things linking against KDE (outside of KDE), and since those are open-source, I can compile my own copies against 64-bit libraries. I was more wanting to know if I'd overlooked any common (or otherwise) tools/applications that link against desktop libraries. – chrisb2244 Feb 18 '15 at 13:36

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