From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: Olivia Mackall <olivia@selenic.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Heiko Stuebner <heiko@sntech.de>,
Philipp Zabel <p.zabel@pengutronix.de>,
Lin Jinhan <troy.lin@rock-chips.com>,
"open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
<linux-crypto@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
"moderated list:ARM/Rockchip SoC support"
<linux-arm-kernel@lists.infradead.org>,
"open list:ARM/Rockchip SoC support"
<linux-rockchip@lists.infradead.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 2/3] hwrng: add Rockchip SoC hwrng driver
Date: Mon, 5 Dec 2022 14:13:45 +0100 [thread overview]
Message-ID: <Y43uiVo41vljLsZM@zx2c4.com> (raw)
In-Reply-To: <20221128184718.1963353-3-aurelien@aurel32.net>
On Mon, Nov 28, 2022 at 07:47:17PM +0100, Aurelien Jarno wrote:
> The TRNG device does not seem to have a signal conditionner and the FIPS
> 140-2 test returns a lot of failures. They can be reduced by increasing
> RK_RNG_SAMPLE_CNT, in a tradeoff between quality and speed. This value
> has been adjusted to get ~90% of successes and the quality value has
> been set accordingly.
Can't you reduce it even more to get 100%? All we need is 32 bytes every
once in a while.
> + rk_rng->rng.quality = 900;
If your intention is "90%", this should be 921 or 922, because the
quality knob is out of 1024, not 1000.
Herbert - this seems like a fairly common pitfall I've seen all over the
place. It might be worth making a mental memo to reject or ask questions
about numbers that seem "too round", when you look at these sorts of
patches.
Jason
WARNING: multiple messages have this Message-ID (diff)
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: Olivia Mackall <olivia@selenic.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Heiko Stuebner <heiko@sntech.de>,
Philipp Zabel <p.zabel@pengutronix.de>,
Lin Jinhan <troy.lin@rock-chips.com>,
"open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
<linux-crypto@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
"moderated list:ARM/Rockchip SoC support"
<linux-arm-kernel@lists.infradead.org>,
"open list:ARM/Rockchip SoC support"
<linux-rockchip@lists.infradead.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 2/3] hwrng: add Rockchip SoC hwrng driver
Date: Mon, 5 Dec 2022 14:13:45 +0100 [thread overview]
Message-ID: <Y43uiVo41vljLsZM@zx2c4.com> (raw)
In-Reply-To: <20221128184718.1963353-3-aurelien@aurel32.net>
On Mon, Nov 28, 2022 at 07:47:17PM +0100, Aurelien Jarno wrote:
> The TRNG device does not seem to have a signal conditionner and the FIPS
> 140-2 test returns a lot of failures. They can be reduced by increasing
> RK_RNG_SAMPLE_CNT, in a tradeoff between quality and speed. This value
> has been adjusted to get ~90% of successes and the quality value has
> been set accordingly.
Can't you reduce it even more to get 100%? All we need is 32 bytes every
once in a while.
> + rk_rng->rng.quality = 900;
If your intention is "90%", this should be 921 or 922, because the
quality knob is out of 1024, not 1000.
Herbert - this seems like a fairly common pitfall I've seen all over the
place. It might be worth making a mental memo to reject or ask questions
about numbers that seem "too round", when you look at these sorts of
patches.
Jason
_______________________________________________
Linux-rockchip mailing list
Linux-rockchip@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-rockchip
WARNING: multiple messages have this Message-ID (diff)
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: Olivia Mackall <olivia@selenic.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Heiko Stuebner <heiko@sntech.de>,
Philipp Zabel <p.zabel@pengutronix.de>,
Lin Jinhan <troy.lin@rock-chips.com>,
"open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
<linux-crypto@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
"moderated list:ARM/Rockchip SoC support"
<linux-arm-kernel@lists.infradead.org>,
"open list:ARM/Rockchip SoC support"
<linux-rockchip@lists.infradead.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 2/3] hwrng: add Rockchip SoC hwrng driver
Date: Mon, 5 Dec 2022 14:13:45 +0100 [thread overview]
Message-ID: <Y43uiVo41vljLsZM@zx2c4.com> (raw)
In-Reply-To: <20221128184718.1963353-3-aurelien@aurel32.net>
On Mon, Nov 28, 2022 at 07:47:17PM +0100, Aurelien Jarno wrote:
> The TRNG device does not seem to have a signal conditionner and the FIPS
> 140-2 test returns a lot of failures. They can be reduced by increasing
> RK_RNG_SAMPLE_CNT, in a tradeoff between quality and speed. This value
> has been adjusted to get ~90% of successes and the quality value has
> been set accordingly.
Can't you reduce it even more to get 100%? All we need is 32 bytes every
once in a while.
> + rk_rng->rng.quality = 900;
If your intention is "90%", this should be 921 or 922, because the
quality knob is out of 1024, not 1000.
Herbert - this seems like a fairly common pitfall I've seen all over the
place. It might be worth making a mental memo to reject or ask questions
about numbers that seem "too round", when you look at these sorts of
patches.
Jason
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-12-05 13:14 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-28 18:47 [PATCH v2 0/3] hwrng: add hwrng support for Rockchip RK3568 Aurelien Jarno
2022-11-28 18:47 ` Aurelien Jarno
2022-11-28 18:47 ` Aurelien Jarno
2022-11-28 18:47 ` [PATCH v2 1/3] dt-bindings: RNG: Add Rockchip RNG bindings Aurelien Jarno
2022-11-28 18:47 ` Aurelien Jarno
2022-11-28 18:47 ` Aurelien Jarno
2022-11-29 9:24 ` Krzysztof Kozlowski
2022-11-29 9:24 ` Krzysztof Kozlowski
2022-11-29 9:24 ` Krzysztof Kozlowski
2022-12-02 19:20 ` Aurelien Jarno
2022-12-02 19:20 ` Aurelien Jarno
2022-12-02 19:20 ` Aurelien Jarno
2022-12-03 10:21 ` Krzysztof Kozlowski
2022-12-03 10:21 ` Krzysztof Kozlowski
2022-12-03 10:21 ` Krzysztof Kozlowski
2022-11-28 18:47 ` [PATCH v2 2/3] hwrng: add Rockchip SoC hwrng driver Aurelien Jarno
2022-11-28 18:47 ` Aurelien Jarno
2022-11-28 18:47 ` Aurelien Jarno
2022-11-29 9:33 ` Krzysztof Kozlowski
2022-11-29 9:33 ` Krzysztof Kozlowski
2022-11-29 9:33 ` Krzysztof Kozlowski
2022-12-02 19:30 ` Aurelien Jarno
2022-12-02 19:30 ` Aurelien Jarno
2022-12-02 19:30 ` Aurelien Jarno
2022-12-05 13:13 ` Jason A. Donenfeld [this message]
2022-12-05 13:13 ` Jason A. Donenfeld
2022-12-05 13:13 ` Jason A. Donenfeld
2022-12-05 13:30 ` Jason A. Donenfeld
2022-12-05 13:30 ` Jason A. Donenfeld
2022-12-05 13:30 ` Jason A. Donenfeld
2022-12-05 21:34 ` Aurelien Jarno
2022-12-05 21:34 ` Aurelien Jarno
2022-12-05 21:34 ` Aurelien Jarno
2022-12-05 21:41 ` Jason A. Donenfeld
2022-12-05 21:41 ` Jason A. Donenfeld
2022-12-05 21:41 ` Jason A. Donenfeld
2022-11-28 18:47 ` [PATCH v2 3/3] arm64: dts: rockchip: add DT entry for RNG to RK356x Aurelien Jarno
2022-11-28 18:47 ` Aurelien Jarno
2022-11-28 18:47 ` Aurelien Jarno
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