From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=FROM_EXCESS_BASE64, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14AECC04A6B for ; Fri, 10 May 2019 15:54:18 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DB50D20881 for ; Fri, 10 May 2019 15:54:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DB50D20881 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:45483 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hP7qj-0004iP-75 for qemu-devel@archiver.kernel.org; Fri, 10 May 2019 11:54:17 -0400 Received: from eggs.gnu.org ([209.51.188.92]:59328) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hP7Vx-0003P6-Pf for qemu-devel@nongnu.org; Fri, 10 May 2019 11:32:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hP7Vu-0002Az-2d for qemu-devel@nongnu.org; Fri, 10 May 2019 11:32:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60584) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hP7Vp-000248-RJ for qemu-devel@nongnu.org; Fri, 10 May 2019 11:32:43 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 181D53082B02; Fri, 10 May 2019 15:32:33 +0000 (UTC) Received: from redhat.com (ovpn-112-68.ams2.redhat.com [10.36.112.68]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 337F55C220; Fri, 10 May 2019 15:32:29 +0000 (UTC) Date: Fri, 10 May 2019 16:32:27 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Laurent Vivier Message-ID: <20190510153227.GO7671@redhat.com> References: <20190510102637.10209-1-lvivier@redhat.com> <87zhnuqyu0.fsf@dusky.pond.sub.org> <87991c2b-da9d-0e7f-bc09-9fbadbda4ef8@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87991c2b-da9d-0e7f-bc09-9fbadbda4ef8@redhat.com> User-Agent: Mutt/1.11.4 (2019-03-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Fri, 10 May 2019 15:32:33 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v2] rng-builtin: add an RNG backend that uses qemu_guest_getrandom() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Kashyap Chamarthy , Markus Armbruster , Amit Shah , Richard Henderson , qemu-devel@nongnu.org, "Richard W . M . Jones" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, May 10, 2019 at 02:37:41PM +0200, Laurent Vivier wrote: > On 10/05/2019 14:27, Markus Armbruster wrote: > > Laurent Vivier writes: > > The new rng-builtin is considerably simpler than both rng-random and > > rng-egd. Moreover, it just works, whereas rng-random is limited to > > CONFIG_POSIX, and rng-egd needs egd running (which I suspect basically > > nobody does). Have we considered deprecating these two backends in > > favor of rng-builtin? > > I have several bugzilla involving these backends: as there are blocking, the > virtio-rng device in the guest can hang, or crash during hot-unplug. From my > point of view, life would be easier without them... Are you sure about that ? The EGD impl looks like it is requesting entropy in an async manner. Any problem with rng-random would also affect rng-builtin, as depending on platform / build options, rng-builtin may just use /dev/urandom directly. It should only block with /dev/random really and that's only with Linux's impl of /dev/random - some OS effectively have /dev/random behave identically to /dev/urandom. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|