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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 9CA78C49ED6 for ; Wed, 11 Sep 2019 19:19:14 +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 6AACE207FC for ; Wed, 11 Sep 2019 19:19:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6AACE207FC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sipsolutions.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:55710 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i8893-0005Zb-LU for qemu-devel@archiver.kernel.org; Wed, 11 Sep 2019 15:19:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57180) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i888K-00056Z-Sl for qemu-devel@nongnu.org; Wed, 11 Sep 2019 15:18:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i888J-0004O5-Eb for qemu-devel@nongnu.org; Wed, 11 Sep 2019 15:18:28 -0400 Received: from s3.sipsolutions.net ([2a01:4f8:191:4433::2]:36534 helo=sipsolutions.net) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i888J-0004MW-78 for qemu-devel@nongnu.org; Wed, 11 Sep 2019 15:18:27 -0400 Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1i888F-0008NC-FI; Wed, 11 Sep 2019 21:18:23 +0200 Message-ID: <24d6940040c4f846eaba2154979fd6658b665c98.camel@sipsolutions.net> From: Johannes Berg To: "Dr. David Alan Gilbert" Date: Wed, 11 Sep 2019 21:18:20 +0200 In-Reply-To: <20190911191514.GA2895@work-vm> References: <20190911134539.25650-1-johannes@sipsolutions.net> <20190911134539.25650-2-johannes@sipsolutions.net> <20190911191514.GA2895@work-vm> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2a01:4f8:191:4433::2 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" 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/ Thanks, johannes