From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-x232.google.com (mail-io0-x232.google.com [IPv6:2607:f8b0:4001:c06::232]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 8B2013B25E for ; Mon, 9 May 2016 11:10:24 -0400 (EDT) Received: by mail-io0-x232.google.com with SMTP id d62so175161902iof.2 for ; Mon, 09 May 2016 08:10:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:subject:from:to:cc:date:in-reply-to:references :mime-version:content-transfer-encoding; bh=XjXcQisiEMXTy8u3l1Mm+C/WPEkxtq+DXrpZe3RXIKY=; b=SPs3MHSMG2e7jKnAGm4vrxw1BWNIJ89kNg6uSwcm1TZycA3uIe2sYv3LVK/I9AqRIb Ltn7MGWBN00PDa/Kvo91cEyFBsAcDZlbschv3vdEUTsyOEuawED7WubkmRcfWF9otNj5 Lru6YtmpW+iTknHc5oZUvM8ut7xupUzFoyflylGG+8rrExcFaRmSvc8K2tv4dVe026RK K9QERq+0oisGOxzTm712ZKErF7QAzmwtc4JFuxAtcP3Bz1Lat7dvcrIZ0cfL+72Oxlhs opjIeW/zj5S75g1KC+f+ukxOnEkNOGU2Sx2QNHmKk212GOjGzt3igB4o7J1PeOtfO4o/ 930g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:mime-version:content-transfer-encoding; bh=XjXcQisiEMXTy8u3l1Mm+C/WPEkxtq+DXrpZe3RXIKY=; b=RQH+r5i/s3xALEl7vI9fGWHJRcYC91ntyhq1WFNKH3Vejlte30WcpRnP0kstaN0WQt 5ePJeL3WOvgcIHb3/bUkHz0wsHeZP2VkixQwjn8rLpQOyxBKM4889xlNH+T2U8Ijd63e CNkysqO4jyLfw3bqb7GRGeOhtnx/P+CHfvsiVstebGhfR90JIGDHyCbPPgzZBv+nGnNX w7sr/SbBfLFvuY6n/r4wTRl5nU2k6lFCUT1tcIMfXsI8rmpBKlkvVqoGeetsbq/ByhNN wd2JtS2xmugJvOZPPQnzHb+Sf78vbfRjW5Fopphcl8IEVJzH2N8rbH3Qlt+IK04dzcnU tl2g== X-Gm-Message-State: AOPr4FWT/gXv8LKEG/bc3rjH/vr/tlS+Xt0BzJ31ou4ys4nRE6gqhnHb8uSi2srH62sByg== X-Received: by 10.107.51.206 with SMTP id z197mr41088124ioz.107.1462806623930; Mon, 09 May 2016 08:10:23 -0700 (PDT) Received: from magrathea (c-50-170-131-39.hsd1.co.comcast.net. [50.170.131.39]) by smtp.googlemail.com with ESMTPSA id ji1sm11525378igb.1.2016.05.09.08.10.22 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 09 May 2016 08:10:23 -0700 (PDT) Message-ID: <1462806622.5898.9.camel@gmail.com> From: Josh Datko To: Dave Taht Cc: "cerowrt-devel@lists.bufferbloat.net" Date: Mon, 09 May 2016 09:10:22 -0600 In-Reply-To: References: <1462464637.25803.30.camel@gmail.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.18.5.2-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: Re: [Cerowrt-devel] pcengines apu2c4 hardware random number generation X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 May 2016 15:10:24 -0000 On Fri, 2016-05-06 at 13:19 -0700, Dave Taht wrote: > On Thu, May 5, 2016 at 9:10 AM, Josh Datko wrote: > >  > I forget how fast those chips were (?) The get_random command, from the perspective of the Atmel chip, takes on average, 11ms to return 32bytes of random numbers, with a max of 50ms (from the ATSHA204A datasheet).  Practically however, you have to account for the kernel processing, 100khz I2C send and return up the stack. > Meh. If there is a decent gpio header on j.random x86 board, I'd just > as soon use that. Yeah, I hear you. What I do is I split my video cable and hijack the i2c and power lines from that (typically used to read the EDID from the monitor) so I can develop on my workstation. You board didn't seem to have a video connection, otherwise I'd suggest that. I made a VGA2I2C board that you can get on OSHPark if you want to solder on some N-channel mosfets and some 0603 resistors. Otherwise, the drivers all use either the kernel's i2c subsytem or in userspace, the ioctl. So, afaik, there'd have to be an i2c-bitbang hardware abstract layer used to use random GPIO pins.