From owner-svn-src-head@freebsd.org Thu Jul 23 08:09:10 2015 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 70FEF9A7C11; Thu, 23 Jul 2015 08:09:10 +0000 (UTC) (envelope-from markm@FreeBSD.org) Received: from gromit.grondar.org (grandfather.grondar.org [IPv6:2a01:348:0:15:5d59:5c20:0:2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 2EB1D11EF; Thu, 23 Jul 2015 08:09:10 +0000 (UTC) (envelope-from markm@FreeBSD.org) Received: from graveyard.grondar.org ([88.96.155.33] helo=gronkulator.grondar.org) by gromit.grondar.org with esmtpsa (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.85 (FreeBSD)) (envelope-from ) id 1ZIBYx-000Laa-8q; Thu, 23 Jul 2015 09:09:07 +0100 Subject: Re: svn commit: r284959 - in head: . share/man/man4 share/man/man9 sys/conf sys/dev/glxsb sys/dev/hifn sys/dev/random sys/dev/rndtest sys/dev/safe sys/dev/syscons sys/dev/ubsec sys/dev/virtio/random sy... Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2102\)) Content-Type: text/plain; charset=utf-8 From: Mark R V Murray In-Reply-To: Date: Thu, 23 Jul 2015 09:09:01 +0100 Cc: src-committers , svn-src-all@freebsd.org, svn-src-head@freebsd.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <201506301700.t5UH0jPq001498@svn.freebsd.org> To: Jeff Roberson X-Mailer: Apple Mail (2.2102) X-SA-Score: -1.0 X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 23 Jul 2015 08:09:10 -0000 > On 23 Jul 2015, at 08:59, Jeff Roberson = wrote: >=20 >>=20 >> OK - I?m sold! I?ll make a kernel option defaulting to off. :-) >=20 > There are other sources that occur less frequently than millions of = times per-second that may still provide some usefull entropy while being = less performance critical under normal conditions. I=E2=80=99m sure there are, and I=E2=80=99m keen to discover more! I=E2=80= =99m not exactly the worlds best kernel hacker, so I=E2=80=99ll be = requesting help. My own crappy benchmark is =E2=80=9Cmake world=E2=80=9D and for that, I = notice very little. For Video at Ludicrous Speed(=E2=84=A2), I=E2=80=99m = well prepared to accept otherwise! For crypto purposes, UMA is = brilliant, though (but that won=E2=80=99t stop me defaulting it to = =E2=80=9Ccompiled out=E2=80=9D). > For example, context switches, traps, etc. I could also imagine = wiring up a pmc counter to something like cache misses or branch = mispredicts that would be more difficult to game, especially if the = counter was cycled irregularly. Help requested here, please! If you could point out suitable harvesting = points, I=E2=80=99ll see if the numbers from them look good. Thanks! M --=20 Mark R V Murray