Date: Tue, 30 Jul 2013 16:07:48 +0200 From: Julian Stecklina <jsteckli@os.inf.tu-dresden.de> To: "O. Hartmann" <ohartman@zedat.fu-berlin.de> Cc: freebsd-current@freebsd.org Subject: Re: CURRENT: Ivy Bridge CPU (i3-3220) and Intel Bull Mountain RNG (options RDRAND_RNG) Message-ID: <51F7C8B4.7070809@os.inf.tu-dresden.de> In-Reply-To: <20130730134635.3b6d7b31@thor.walstatt.dyndns.org> 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
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