Apache Start Hangs during Reboot of a KVM Virtual Server

Problem: Apache needs very long to start on a virtual server running on a KVM/QEMU virtual maschine.

Solution: Apache needs a RNG (random number generator) for startup, probably because of TLS. A pure virtual maschine has no RNG device per default. If you add an RNG device to the virtual maschine configuration, apache startup is lightening fast.

    <rng model='virtio'>
      <backend model='random'>/dev/random</backend>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </rng>

Versions: tested with libvirt 3.0.0, qemu-kvm 2.8 on devuan 9