Arm SMCCC TRNG Driver Queued Ahead Of Linux 5.15

The Linux kernel already supports making use of Arm's True Random Number Generator (TRNG) SMCCC interface within the random seed code while for the upcoming Linux 5.15 cycle an "arm_smccc_trng" driver is being added and will allow exposing the entropy to user-space.

Arm defines this true random number generator firmware interface and is used for seeding the random pool and can also be used by KVM virtualized guests too. Arguably what's overdue but now happening is providing this Arm SMCCC TRNG driver for exposing the entropy in an easy manner to user-space. With this new driver, the entropy from this firmware interface can be exposed via /dev/hwrng. In turn this is useful for being able to verify the quality of the entropy with the likes of rng-tool's rngtest utility and the like. Thus easier to evaluate and put trust into this firmware interface for TRNG needs.

The Arm True Random Number Generator Firmware Interface 1.0 was released last year and ultimately backed by a hardware device like Arm TrustZone's TRNG or other raw noise.

The new driver contributed by Arm is queued into the "cryptodev" Git tree ahead of the Linux 5.15 merge window opening in a few weeks.