From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Mackerras Subject: Re: [PATCH 0/2] Add support for Qualcomm's PRNG Date: Thu, 10 Oct 2013 21:41:40 +1100 Message-ID: <20131010104140.GE9906@iris.ozlabs.ibm.com> References: <1380811955-18085-1-git-send-email-svarbanov@mm-sol.com> <20131003165130.GA11974@thunk.org> <524EEB96.6040707@mm-sol.com> <20131004181005.GA7022@thunk.org> <52556C4E.9000604@mm-sol.com> <52557137.5050200@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from ozlabs.org ([203.10.76.45]:48500 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755052Ab3JJKmT (ORCPT ); Thu, 10 Oct 2013 06:42:19 -0400 Content-Disposition: inline In-Reply-To: <52557137.5050200@zytor.com> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: "H. Peter Anvin" Cc: Stanimir Varbanov , Theodore Ts'o , Rob Herring , Pawel Moll , Mark Rutland , Stephen Warren , Ian Campbell , Matt Mackall , Herbert Xu , linux-kernel@vger.kernel.org, Rob Landley , devicetree@vger.kernel.org, linux-doc@vger.kernel.org, Greg Kroah-Hartman , linux-arm-msm@vger.kernel.org On Wed, Oct 09, 2013 at 08:07:35AM -0700, H. Peter Anvin wrote: > consider the PowerPC random number generator[1]) and [snip] > [1] which has a known first-order bias which they "correct" for by > XORing two datums together in a very simple data reduction step. 65 actually, not two. > However, if their random source has bias it is extremely likely it also > has nonzero correlations, which require stronger reductions. It would The correlations are essentially zero, by design, and experiment confirms it. Did you see my mail on the kvm list where I explained how it works? Paul.