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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 2468BC49ED9 for ; Thu, 12 Sep 2019 08:10:23 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EFCF32075C for ; Thu, 12 Sep 2019 08:10:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EFCF32075C 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 ([::1]:59024 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i8KBK-0004mv-3q for qemu-devel@archiver.kernel.org; Thu, 12 Sep 2019 04:10:22 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:58459) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i8KAg-0004L6-6H for qemu-devel@nongnu.org; Thu, 12 Sep 2019 04:09:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i8KAf-0006A1-6n for qemu-devel@nongnu.org; Thu, 12 Sep 2019 04:09:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45588) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i8KAf-00069d-0v for qemu-devel@nongnu.org; Thu, 12 Sep 2019 04:09:41 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 05EAA18CB8E1; Thu, 12 Sep 2019 08:09:39 +0000 (UTC) Received: from work-vm (unknown [10.36.118.12]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5993D600C4; Thu, 12 Sep 2019 08:09:35 +0000 (UTC) Date: Thu, 12 Sep 2019 09:09:32 +0100 From: "Dr. David Alan Gilbert" To: Johannes Berg Message-ID: <20190912080932.GA2722@work-vm> References: <20190911134539.25650-1-johannes@sipsolutions.net> <20190911134539.25650-2-johannes@sipsolutions.net> <20190911191514.GA2895@work-vm> <24d6940040c4f846eaba2154979fd6658b665c98.camel@sipsolutions.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <24d6940040c4f846eaba2154979fd6658b665c98.camel@sipsolutions.net> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.63]); Thu, 12 Sep 2019 08:09:39 +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] [RFC v2 1/2] docs: vhost-user: add in-band kick/call messages X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, "Michael S . Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Johannes Berg (johannes@sipsolutions.net) wrote: > On Wed, 2019-09-11 at 20:15 +0100, Dr. David Alan Gilbert wrote: > > > > Extend the protocol slightly, so that a message can be used for kick > > > and call instead, if VHOST_USER_PROTOCOL_F_IN_BAND_NOTIFICATIONS is > > > negotiated. This in itself doesn't guarantee synchronisation, but both > > > sides can also negotiate VHOST_USER_PROTOCOL_F_REPLY_ACK and thus get > > > a reply to this message by setting the need_reply flag, and ensure > > > synchronisation this way. > > > > I'm confused; if you've already got REPLY_ACK, why do we need anything > > else? We already require the reply on set_mem_table as part of > > postcopy. > > Hmm? How's this related to set_mem_table? > > For simulation purposes, I need the kick and call (and error perhaps > though it's not really used by anyone now it seems) to be synchronous > messages instead of asynchronous event FD pushes. > > But I think enough words have been expended on explaining it already, if > I may kindly ask you to read the discussions with Stefan and Michael > here: > > https://lore.kernel.org/qemu-devel/20190902121233.13382-1-johannes@sipsolutions.net/ Ah OK. You're actually using the same trick of using REPLY_ACK/need_reply to make it synchronous that set_mem_table does; that makes sense - but then new calls are getting it to actually process some data/commands on the ring itself? Dave > Thanks, > johannes > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK