jitterentropy-rngd binary package in Ubuntu Oracular s390x

 Using the Jitter RNG core, the rngd provides an entropy source that
 feeds into the Linux /dev/random device if its entropy runs low. It
 updates the /dev/random entropy estimator such that the newly provided
 entropy unblocks /dev/random.
 .
 The seeding of /dev/random also ensures that /dev/urandom benefits from
 entropy. Especially during boot time, when the entropy of Linux is low,
 the Jitter RNGd provides a source of sufficient entropy.

Source package