From: Stephan Mueller Subject: Re: [PATCH 2/2] ath9k: disable RNG by default Date: Tue, 09 Aug 2016 11:37:39 +0200 Message-ID: <1645997.7cVzaEi3NG@tauon.atsec.com> References: <1470726147-30095-1-git-send-email-miaoqing@codeaurora.org> <2569442.q63FVBJjUH@tauon.atsec.com> <20160809091755.GA6370@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: "Pan, Miaoqing" , Matt Mackall , "miaoqing-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org" , "Valo, Kalle" , "linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , ath9k-devel , "linux-crypto-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "jason-NLaQJdtUoK4Be96aLqz0jA@public.gmane.org" , "Sepehrdad, Pouyan" To: Herbert Xu Return-path: In-Reply-To: <20160809091755.GA6370-lOAM2aK0SrRLBo1qDEOMRrpzq4S04n8Q@public.gmane.org> Sender: linux-wireless-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-crypto.vger.kernel.org Am Dienstag, 9. August 2016, 17:17:55 CEST schrieb Herbert Xu: Hi Herbert, > On Tue, Aug 09, 2016 at 11:02:58AM +0200, Stephan Mueller wrote: > > But shouldn't the default of the rngd then be adjusted a bit? > > Please elaborate. in rngd_linux.c:random_add_entropy(void *buf, size_t size): entropy.ent_count = size * 8; entropy.size = size; memcpy(entropy.data, buf, size); if (ioctl(random_fd, RNDADDENTROPY, &entropy) != 0) { ... in rngd.c:do_loop(): retval = iter->xread(buf, sizeof buf, iter); ... rc = update_kernel_random(random_step, buf, iter->fipsctx); where update_kernel_random simply invokes random_add_entropy in chunks. Hence, the rngd reads some bytes from /dev/hwrand and injects it into /dev/ random with an entropy estimate that is equal to the read bytes. With less than perfect noise sources, entropy.ent_count should be much smaller. > > Thanks, Ciao Stephan -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html