Re: [PATCH 1/1] tpm: disable hwrng for fTPM on some AMD designs

From: Mateusz Schyboll
Date: Tue Aug 01 2023 - 07:42:54 EST


I was following the issue under or discord channel ROG for Linux and helping out some other users with it by shipping a kernel for Arch with disabled CONFIG_HW_RANDOM_TPM as the default recommend kernel for Arch for ROG laptops (as my device isn't affect by it because it is Ryzen 4800HS).

I know it was discussed here https://bugzilla.kernel.org/show_bug.cgi?id=217212#c16 against allowing the user to disable fTPM to be used as a random source via a boot time parameter but I still I disagree with it.

Linux does have a parameter `random.trust_cpu` to control the random source from CPU, why they can not be a parameter like `random.trust_ftpm` (or `random.trust_tpm`)?

It might be my limited knowledge of this topic but to me it feels like if they is a trust_cpu then Linux should have trust_ftpm too.

Mateusz