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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 B974DC433E0 for ; Mon, 20 Jul 2020 11:10:38 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 893C42068F for ; Mon, 20 Jul 2020 11:10:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b="G2oLYpai" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 893C42068F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=citrix.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jxTgY-0005u2-0O; Mon, 20 Jul 2020 11:10:18 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jxTgX-0005tx-29 for xen-devel@lists.xenproject.org; Mon, 20 Jul 2020 11:10:17 +0000 X-Inumbo-ID: 96897620-ca79-11ea-9f84-12813bfff9fa Received: from esa1.hc3370-68.iphmx.com (unknown [216.71.145.142]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 96897620-ca79-11ea-9f84-12813bfff9fa; Mon, 20 Jul 2020 11:10:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1595243417; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=0uY2iAGgQD/jTVNZ02tjyg9+PVJ6iVv1+aMXh5h7mv4=; b=G2oLYpaiKtgu8nq2PNqXJhIkR4SZVuinh/bqfn7hF5AR96+1VSCHeoEu B8fGYj5YMlBM2IZKWba5pEQldUPiqZZHtkaolMpecs35wlhnbzqYGfscW b15G2LQPkKfj9gvHZOyLLA5Lqon4TEvyCKMowU22LZhuDSADxuJPKMXaT I=; Authentication-Results: esa1.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none IronPort-SDR: d/9RX8s/l3kWpPI01lNkPjuqD1aCI7h9a+pqnZQ6piT5cn3wv5f75X4vtxfd2b9ILqf4TEcWTA GR4Cs59sV7u/5O64zLToBz8IjvueaLL7j8JL5Nvsk/lqmdnDAbhDh/uVrxZz4ZvcNjqBNvKBCX NkjyUruM3YGVy1QzqcxvNBk6ggOTWWRtFMGr1xJtOe3S1y0OnYif5sv9GRdpRqBAAXJQ2xZCNY NhyIRm1BLWJOpxioMDUn/5Gj9rhtP5KiQAdOcCpAlW07CpV5aPOXgfxbA+3t6CWzgyUWu6zkjf Z3c= X-SBRS: 2.7 X-MesageID: 23066242 X-Ironport-Server: esa1.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.75,374,1589256000"; d="scan'208";a="23066242" Date: Mon, 20 Jul 2020 13:09:50 +0200 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Oleksandr Subject: Re: Virtio in Xen on Arm (based on IOREQ concept) Message-ID: <20200720110950.GJ7191@Air-de-Roger> References: <20200717150039.GV7191@Air-de-Roger> <8f4e0c0d-b3d4-9dd3-ce20-639539321968@gmail.com> <20200720091722.GF7191@Air-de-Roger> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-ClientProxiedBy: AMSPEX02CAS02.citrite.net (10.69.22.113) To AMSPEX02CL02.citrite.net (10.69.22.126) X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Stefano Stabellini , Julien Grall , Oleksandr Andrushchenko , Bertrand Marquis , xen-devel , Artem Mygaiev Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On Mon, Jul 20, 2020 at 01:56:51PM +0300, Oleksandr wrote: > On 20.07.20 12:17, Roger Pau Monné wrote: > > On Fri, Jul 17, 2020 at 09:34:14PM +0300, Oleksandr wrote: > > > On 17.07.20 18:00, Roger Pau Monné wrote: > > > > On Fri, Jul 17, 2020 at 05:11:02PM +0300, Oleksandr Tyshchenko wrote: > > > The other reasons are: > > > > > > 1. Automation. With current backend implementation we don't need to pause > > > guest right after creating it, then go to the driver domain and spawn > > > backend and > > > > > > after that go back to the dom0 and unpause the guest. > > xl devd should be capable of handling this for you on the driver > > domain. > > > > > 2. Ability to detect when guest with involved frontend has gone away and > > > properly release resource (guest destroy/reboot). > > > > > > 3. Ability to (re)connect to the newly created guest with involved frontend > > > (guest create/reboot). > > > > > > 4. What is more that having Xenstore support the backend is able to detect > > > the dom_id it runs into and the guest dom_id, there is no need pass them via > > > command line. > > > > > > > > > I will be happy to explain in details after publishing backend code). > > As I'm not the one doing the work I certainly won't stop you from > > using xenstore on the backend. I would certainly prefer if the backend > > gets all the information it needs from the command line so that the > > configuration data is completely agnostic to the transport layer used > > to convey it. > > > > Thanks, Roger. > > Thank you for pointing another possible way. I feel I need to investigate > what is the "xl devd" (+ Argo?) and how it works. If it is able to provide > backend with That's what x86 at least uses to manage backends on driver domains: xl devd will for example launch the QEMU instance required to handle a Xen PV disk backend in user-space. Note that there's currently no support for Argo or any communication channel different than xenstore, but I think it would be cleaner to place the fetching of data from xenstore in xl devd and just pass those as command line arguments to the VirtIO backend if possible. I would prefer the VirtIO backend to be fully decoupled from xenstore. Note that for a backend running on dom0 there would be no need to pass any data on xenstore, as the backend would be launched directly from xl with the appropriate command line arguments. > the support/information it needs and xenstore is not welcome then I would be > absolutely ok to consider using other solution. > > I propose to get back to that discussion after I prepare and send out the > proper IOREQ series. Sure, that's fine. Roger.