The TPM security chip that is available in most modern systems has a hardware RNG.
It is also used to feed the entropy pool, but generally not credited entropy.
Use rng_core.default_quality in the kernel command line to set the trust
level on the hardware generators. The trust level defines the amount of entropy to credit.
A value of 0 tells the system not to trust the hardware random number generators
available, and doesn't credit any entropy to the pool.
A value of 1000 assigns full confidence in the generators, and credits all the
entropy it provides to the pool.
Note that the value of rng_core.default_quality is global, affecting the trust
on all hardware random number generators.
Select the appropriate confidence by adding the argument
rng_core.default_quality= to the default
GRUB 2 command line for the Linux operating system.
Configure the default Grub2 kernel command line to contain rng_core.default_quality= as follows:
# grub2-editenv - set "$(grub2-editenv - list | grep kernelopts) rng_core.default_quality="