Re: [PATCH v2 6/9] powerpc/microwatt: Add support for hardware random number generator

Excerpts from Segher Boessenkool's message of June 20, 2021 12:36 am:

On Sat, Jun 19, 2021 at 01:08:51PM +1000, Nicholas Piggin wrote:

quoted

Excerpts from Paul Mackerras's message of June 18, 2021 1:47 pm:

quoted

Microwatt's hardware RNG is accessed using the DARN instruction.

I think we're getting a platforms/book3s soon with the VAS patches, 
might be a place to add the get_random_darn function.

Huh, DARN is unprivileged right?

It is, that's the whole point: to make it very very cheap for user
software it has to be an unprivileged instruction.

Right, I was just doing a double-take. In that case we should enable it 
in the pseries random number code as well, so it really would be a 
generic isa 3.0 function that all (microwatt, powernv, pseries) could
use AFAIKS.

Thanks,
Nick