https://docs.kernel.org/admin-guide/pm/amd-pstate.html
The pstate driver should be compiled into the kernel
CONFIG_X86_AMD_PSTATE=y CONFIG_X86_AMD_PSTATE_DEFAULT_MODE=3
Then it could be optionally enabled with an config command:
set system option kernel amd-pstate-driver (active|passive|guided)
which sets the kernel argument to initcall_blacklist=acpi_cpufreq_init amd_pstate=guide to enable the amd pstate_driver on AMD Ryzen/Epyc CPUs