Skip to content
Commit fae29f13 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Herbert Xu
Browse files

hwrng: core - document the quality field



quality field is currently documented as being 'per mill'.  In fact the
math involved is:

                add_hwgenerator_randomness((void *)rng_fillbuf, rc,
                                           rc * current_quality * 8 >> 10);

thus the actual definition is "bits of entropy per 1024 bits of input".

The current documentation seems to have confused multiple people
in the past, let's fix the documentation to match code.

An alternative is to change core to match driver expectations, replacing
	rc * current_quality * 8 >> 10
with
	rc * current_quality / 1000
but that has performance costs, so probably isn't a good option.

Fixes: 0f734e6e ("hwrng: add per-device entropy derating")
Reported-by: default avatar"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 3512dcb4
Loading
Loading
Loading
Loading
0% Loading or .
You are about to add 0 people to the discussion. Proceed with caution.
Please register or to comment