virtualbox does not warn appropriately when kernel bitness and binary bitness differ

You cannot run an i386 virtualbox binary on an amd64 kernel with otherwise mostly i386 userland. I was told by upstream that binary bitness for the virtualhost binary package and kernel bitness have to be the same.

The error message when attempting to start an image in that scenario is probably not helpful in pinpointing the problem even for a technical person.

==========================================
RTR3InitEx failed with rc=-1912 (rc=-1912)

The VirtualBox kernel modules do not match this version of VirtualBox. The installation of VirtualBox was apparently not successful. Executing

'/etc/init.d/vboxdrv setup'

may correct this. Make sure that you do not mix the OSE version and the PUEL version of VirtualBox.

Details:
where: supR3HardenedMainInitRuntime
what: 4
VERR_VM_DRIVER_VERSION_MISMATCH (-1912) - The installed support driver doesn't match the version of the user.
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The suggested fix is unlikely to bring the user any closer to a resolution even if bug 1665419 wouldn't stop it dead in its tracks.

What I think needs to happen is to collaborate with upstream to make the error message more meaning- and helpful.

$ apt-cache policy virtualbox-dkms
virtualbox-dkms:
  Installed: 4.3.36-dfsg-1+deb8u1ubuntu1.14.04.1
  Candidate: 4.3.36-dfsg-1+deb8u1ubuntu1.14.04.1
  Version table:
 *** 4.3.36-dfsg-1+deb8u1ubuntu1.14.04.1 0
        500 http://jp.archive.ubuntu.com/ubuntu/ trusty-security/multiverse i386 Packages
        500 http://jp.archive.ubuntu.com/ubuntu/ trusty-updates/multiverse i386 Packages
        100 /var/lib/dpkg/status
     4.3.10-dfsg-1 0
        500 http://jp.archive.ubuntu.com/ubuntu/ trusty/multiverse i386 Packages