From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Tso Subject: Re: [PATCH] drivers/net: remove network drivers' last few uses of IRQF_SAMPLE_RANDOM Date: Thu, 15 May 2008 18:27:41 -0400 Message-ID: <20080515222741.GQ18825@mit.edu> References: <20080515142154.0595e475@core> <36D9DB17C6DE9E40B059440DB8D95F52052D71BB@orsmsx418.amr.corp.intel.com> <20080515215517.GI1936@cs181133002.pp.htv.fi> <482CB354.3010205@garzik.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Adrian Bunk , "Brandeburg, Jesse" , Alan Cox , Chris Peterson , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, mpm@selenic.com To: Jeff Garzik Return-path: Received: from www.church-of-our-saviour.org ([69.25.196.31]:58336 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751867AbYEOW2M (ORCPT ); Thu, 15 May 2008 18:28:12 -0400 Content-Disposition: inline In-Reply-To: <482CB354.3010205@garzik.org> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, May 15, 2008 at 06:04:04PM -0400, Jeff Garzik wrote: >> I have seen embedded systems with zero entropy, and dubious entropy might >> there be better than no entropy at all. >> Or am I wrong on the latter? > > It's also relevant to the discussion to note that input data to kernel > devrandom is mixed, and we can control the amount of "credit" applied to > incoming entropy. Sure, and one possible thing to do is to simply always input the interrupt information to the random number generator, but give it a "entropy credit" of 0. That has the net result of potentially improving the entropy found in /dev/random and /dev/urandom, but not necessarily compromising /dev/random, since /dev/random's output is throttled by the entropy estimate. The only cost of doing this would be the overhead in sending the information into the entropy pool. - Ted