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Date: Tue, 30 Jul 2013 16:07:48 +0200
From: Julian Stecklina <jsteckli@os.inf.tu-dresden.de>
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To: "O. Hartmann" <ohartman@zedat.fu-berlin.de>
Subject: Re: CURRENT: Ivy Bridge CPU (i3-3220) and Intel Bull Mountain RNG
 (options RDRAND_RNG)
References: <20130730134635.3b6d7b31@thor.walstatt.dyndns.org>
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On 07/30/2013 01:46 PM, O. Hartmann wrote:
> 
> I tried the new option "options RDRAND_RNG" on my SOHO server, equipted
> with a Intel i3-3220 "Ivy Brdige" CPU, which is supposed to have the
> Bull Mountain random number generator as a piece of hardware in its
> uncore.
>
> Enabling the kernel option doesn't reveal any presence of such a
> hardware number generator. "sysct kern.random" always reports 
> 
> kern.random.adaptors:  yarrow
> 
> By intentionally disallowing yarrow via commenting out options
> YARROW_RNG, the box reports "no adaptors loaded". So, either this Ivy
> Bridge has been castrated and ripped off by Intel of its RNG or FreeBSD
> isn't capable of detecting it properly or I'm incapable of properly
> configure the kernel.

This might be Erratum BV54:

Problem:
On processors that support the RDRAND instruction, that capability
should be reported via the setting of CPUID.01H:ECX.RDRAND[bit 30]. Due
to this erratum, that bit will not be set, and the execution of the
RDRAND instruction will result in a #UD exception.

Implication:
Software will not be able to utilize the RDRAND instruction

http://www.intel.de/content/dam/www/public/us/en/documents/specification-updates/3rd-gen-core-desktop-specification-update.pdf

Julian