From owner-freebsd-arm@freebsd.org Wed Jul 20 08:12:14 2016 Return-Path: Delivered-To: freebsd-arm@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 DD445B9D87B for ; Wed, 20 Jul 2016 08:12:14 +0000 (UTC) (envelope-from jiashiun@gmail.com) Received: from mail-vk0-x231.google.com (mail-vk0-x231.google.com [IPv6:2607:f8b0:400c:c05::231]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 8E0B81E3B for ; Wed, 20 Jul 2016 08:12:14 +0000 (UTC) (envelope-from jiashiun@gmail.com) Received: by mail-vk0-x231.google.com with SMTP id x130so59008692vkc.0 for ; Wed, 20 Jul 2016 01:12:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=tMSNuzI06gh52W/2U2MXt7eYfPzcI3R1/lJd5tqY5Uc=; b=qTVVXQdIo5XamASQx7DzuGzSVn6dLiBT8hnJRMlmdwuJseTYDO1+4r4znFQ5a845Rp hbB93zUG1qpipxVmoYZGog65xUwm2Ch8n8SSHLy1Yk802ryaUM3NtVxQw1L8qdCEKjJU mR0fdHpFxxXb2Z/9cbYnZhS+/At/EruM2lKAbUBLqKXDIXUJxeTD0IhIA/OLTylpihMH 4Sh0IiIAe5PBRTi+/2v7CBifRf8hFwMv4rVn1kQOyy77S0L8cB2Py5cnPW9P6qJmNUN8 sDc9MvShc8G0W7N0n1/uFjNINcAy4tFV2AZMeF/SC86Z7puEIAvEcZCDpXIzVSgiRwg/ Ihdg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=tMSNuzI06gh52W/2U2MXt7eYfPzcI3R1/lJd5tqY5Uc=; b=Z7f4fLlU0K6FDqjkXOtgJTkuSSfVB17mfbptF0Bf5FXBj/rO7CeQVHpX9H9FCOYROk yPiZoTPIQoFvOJ1i9++WrFR2BKWO/fVBEPwwy2SLBxDW/1cdhe8VRAJgzCPWeNwmVbZc QaOnvPkp75GUcqzwfLRgeYBHM4m+0isKhKNtvNZRsj3pyqkAFHMj8xRtGJAhkaDo8+Xg p05ec4mAqYUZFsi7/aJ75fAGGcBC674n6vZm/8gZI62N0N8IAHVeSNLtes0Wy9mLOeBt BAFGEYbFiIJCZ01yS/FoRi2e114s0mt8UkYGnjalxlZbBdLbjjcBd3hvROYGzccFgwMv ySMw== X-Gm-Message-State: ALyK8tKXO6iNVL+bZA/QyGFk+oArkDuO/lJMVDdqwCKoGxn9CVnbrK5iXEHrOhHlrgwgkNp9tHKRUDH3YEjqxg== X-Received: by 10.31.114.203 with SMTP id n194mr22303842vkc.55.1469002333700; Wed, 20 Jul 2016 01:12:13 -0700 (PDT) MIME-Version: 1.0 Received: by 10.176.0.237 with HTTP; Wed, 20 Jul 2016 01:11:44 -0700 (PDT) In-Reply-To: <20160718115455.10fa95bb@juniper.net> References: <5d8ec4d4-4c36-139d-6102-4fdb200fdf65@gmail.com> <790435eb-f3fc-8d4c-4231-e3cfbf93157b@gmail.com> <20160718115455.10fa95bb@juniper.net> From: Jia-Shiun Li Date: Wed, 20 Jul 2016 16:11:44 +0800 Message-ID: Subject: Re: Random number generator on rpi To: Steve Kiernan Cc: "Jukka A. Ukkonen" , "freebsd-arm@freebsd.org" Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.22 X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 20 Jul 2016 08:12:15 -0000 On Mon, Jul 18, 2016 at 11:54 PM, Steve Kiernan wrote: > > You might want to see my RPi rng driver review up on Phabricator. > It is interrupt driven, which keeps the CPU utilization down to a fraction > of a percent, whereas using a callout or other method easily consumes much > more of the CPU. > > The review is here: > https://reviews.freebsd.org/D6888 > > Note that for RBG (random bit generator) like the one in the RPi, they are > not really RNGs themselves but random bit sources that must be processed > by other algorithms to generate random numbers. So even if one were to grab > the data to test for "randomness", one would need to not assume the rndtest > would necessarily be appropriate, since the values returned by the RBG are > not to be used directly as random numbers without post-processing. > > -Steve > I saw it committed yesterday. Great & thanks! BTW does it have any other document other than http://pastehtml.com/view/crkxyohmp.rtxt as mentioned in https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=19334&start=275 ? I cannot find any other source of info other than linux source and the above link... -Jia-Shiun.