After upgrading util-linux to version 2.32, mkfs.ext4 blocks just for 2
seconds when CRNG is not fully initialized, what I think is acceptable.
Therefore, this bug can be closed.
The reason was described by Theodore Y. Ts'o and following comments here:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=897572#184
This 2-second block can be entirely avoided by providing virtio-rng
device to VM, as Theodore Y. Ts'o already wrote:
-object rng-random,filename=/dev/urandom,id=rng0 \
-device virtio-rng-pci,rng=rng0
In Debian CONFIG_HW_RANDOM_VIRTIO=m, so 'virtio_rng' needs to be added
to initramfs modules (/etc/initramfs-tools/modules) in order to use the
virtio-rng device during boot.
