Re: [PATCH] hwrng: bcm2835: set quality to 1000

Hi Andrew,

I ran rngtest and this is what I got:
root@OpenWrt:/# cat /dev/hwrng | rngtest -c 1000
rngtest 6.10
Copyright (c) 2004 by Henrique de Moraes Holschuh
This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

rngtest: starting FIPS tests...
rngtest: bits received from input: 20000032
rngtest: FIPS 140-2 successes: 996
rngtest: FIPS 140-2 failures: 4
rngtest: FIPS 140-2(2001-10-10) Monobit: 0
rngtest: FIPS 140-2(2001-10-10) Poker: 0
rngtest: FIPS 140-2(2001-10-10) Runs: 1
rngtest: FIPS 140-2(2001-10-10) Long run: 3
rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
rngtest: input channel speed: (min=146.002; avg=349.394; max=1302083.333)Kibits/s
rngtest: FIPS tests speed: (min=12.126; avg=22.750; max=23.432)Mibits/s
rngtest: Program run time: 56826982 microseconds

996 successes and 4 failures -> 99.6% success rate
1024 * 99.6% = 1019 (rounded down to 1000)

I'm not sure if I can rely on rngtest for that...

Best regards,
Álvaro.

El 20/02/2021 a las 20:09, Andrew Lunn escribió:

On Sat, Feb 20, 2021 at 06:47:40PM +0100, Álvaro Fernández Rojas wrote:

quoted

This allows devices without a high precission timer to reduce boot from >100s
to <30s.

diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c
index 1a7c43b43c6b..4b48cb7176b0 100644
--- a/drivers/char/hw_random/bcm2835-rng.c
+++ b/drivers/char/hw_random/bcm2835-rng.c

@@ -163,6 +163,7 @@ static int bcm2835_rng_probe(struct platform_device *pdev)
  	priv->rng.init = bcm2835_rng_init;
  	priv->rng.read = bcm2835_rng_read;
  	priv->rng.cleanup = bcm2835_rng_cleanup;
+	priv->rng.quality = 1000;

Hi Alvero

  * @quality:		Estimation of true entropy in RNG's bitstream
  *			(in bits of entropy per 1024 bits of input;
  *			valid values: 1 to 1024, or 0 for unknown).

How did you determine this device produces 1000 bits of true entropy
per 1024?

     Andrew