Linux early post boot low entropy in /dev/urandom

In Summary :

In other words, the intent is that none of the early randomness, in particular
device randomness, should be discarded.

rand_initialize() starts by "initializing" the input_pool and the blocking_pool
by mixing some extra entropy into them (real time, multiple time stamp counters
and the utsname); it doesn't clear the pools to avoid clobbering existing
entropy.
The primary_crng, however, is fully reinitialized, discarding its existing
state[...]

kindly refer the following link as follow up :
https://ift.tt/2HDO59I