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=-0.3 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 7B7C2C33CB1 for ; Tue, 14 Jan 2020 10:21:25 +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 45750207FF for ; Tue, 14 Jan 2020 10:21:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="usNu8LKR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 45750207FF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:36344 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1irJK8-0001jz-3g for qemu-devel@archiver.kernel.org; Tue, 14 Jan 2020 05:21:24 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:40610) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1irJJ9-000156-5Y for qemu-devel@nongnu.org; Tue, 14 Jan 2020 05:20:24 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1irJJ7-0006A4-VS for qemu-devel@nongnu.org; Tue, 14 Jan 2020 05:20:23 -0500 Received: from mail-qk1-x743.google.com ([2607:f8b0:4864:20::743]:37400) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1irJJ7-00069n-R9 for qemu-devel@nongnu.org; Tue, 14 Jan 2020 05:20:21 -0500 Received: by mail-qk1-x743.google.com with SMTP id 21so11586427qky.4 for ; Tue, 14 Jan 2020 02:20:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=HI8Gr6zHhG3Vukw1huvIV1a1LkKhMaZLUP/apOK5HcI=; b=usNu8LKRxT5BAMzXggB6H2tlmSv+md92rqf6ZofBkMjI8JswsDmLyb73ca380aN0uM GQJ2Mnm959+7XRKy3bTZx3Hho7jbo5TZd2Bubh06+BYYfcZN2glWmCulOQYiJSqyew42 JEU9O08NYaDQvdDhzjxGkbetadhZ+m2/rcmikks27t00hrACdIXxHNhYpV9yEmClQhXG IIvGxDXDROdX0DrvQNbYxhPaagdwYYIPvpB9bH0UorQ5aqz7CqtyWjvfbdTunhEVuIDh 4QyuWJS0wVHfeg1yoWfIOA+qxvd/QTEExqEzCuwV9IMhZrS5G3PtM/x3V7r8gg12pe/c hp9g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=HI8Gr6zHhG3Vukw1huvIV1a1LkKhMaZLUP/apOK5HcI=; b=evOjaqeQOjCOB5TMkybL9s6mYshepsYFJs2kCbVRZd04/4jYUmAf8g/zvpzi+ODcGw U6d2n49jKuyKQJuajSbn9V3IRAnHzLxY2regRCp67E01aVhzymDAK5aRaJaTVNBaBUBw fMh1qKxD24CMkpiuZVHezlUVtJCCdM8ZQYtTrtsIFSoybI3p4W4quxgDwdbEhuG/8SI+ RSQYhgKIhKfHuj3Mc6HeOabRe5kaihVC+jjzNiL7Df4d9HtUum2mVGY1KpoJyB9OLnKR AZFh+BpwqNHowGhMae0Lv9X1+37/4pzynOPtia0FQpPZPEEqN/gMwVuoUhA0j5IMXRrY hgPg== X-Gm-Message-State: APjAAAUuD2jKpVAP0Qc5/Ykf1KyVrZofiZy2EgOSGV4FpuSKlMZgMN/2 keu3brj7LVcP7zXvBovP+6c/kp/BuUZwRgZGfIw= X-Google-Smtp-Source: APXvYqwaVD/HZYWrSWjnP0IWPVxkjm0fHXzCztkPywB8RZXUoGRYdO1NpnhDGKlQsav+Qaz9BxjxuVSS33OF8y0atEk= X-Received: by 2002:a37:a215:: with SMTP id l21mr15927039qke.87.1578997220893; Tue, 14 Jan 2020 02:20:20 -0800 (PST) MIME-Version: 1.0 References: <98d1e1f0-0e53-d207-78ce-ea9717673985@winaoe.org> In-Reply-To: From: Stefan Hajnoczi Date: Tue, 14 Jan 2020 10:20:09 +0000 Message-ID: Subject: Re: [PATCH/RFC 0/1] Vhost User Cross Cable: Intro To: "V." 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X-Received-From: 2607:f8b0:4864:20::743 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: =?UTF-8?B?TWFyYy1BbmRyw6kgTHVyZWF1?= , QEMU Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Jan 10, 2020 at 10:34 AM Marc-Andr=C3=A9 Lureau wrote: > On Wed, Jan 8, 2020 at 5:57 AM V. wrote: Hi V., I think I remember you from Etherboot/gPXE days :). > > 3. > > Now if Cross Cable is actually a new and (after a code-rewrite of 10) a= viable way to connect 2 QEMU's together, could I actually > > suggest a better way? > > I am thinking of a '-netdev vhost-user-slave' option to connect (as cli= ent or server) to a master QEMU running '-netdev vhost-user'. > > This way there is no need for any external program at all, the master c= an have it's memory unshared and everything would just work > > and be fast. > > Also the whole thing can fall back to normal virtio if memory is not sh= ared and it would even work in pure usermode without any > > context switch. > > > > Building a patch for this idea I could maybe get around to, don't clear= ly have an idea how much work this would be but I've done > > crazier things. > > But is this is something that someone might be able to whip up in an ho= ur or two? Someone who actually does have a clue about vhost > > and virtio maybe? ;-) > > I believe https://wiki.qemu.org/Features/VirtioVhostUser is what you > are after. It's still being discussed and non-trivial, but not very > active lately afaik. virtio-vhost-user is being experimented with in the SPDK community but there has been no activity on VIRTIO standardization or the QEMU patches for some time. More info here: https://ndragazis.github.io/spdk.html I think the new ivshmem v2 feature may provide the functionality you are looking for, but I haven't looked at them yet. Here is the link: https://www.mail-archive.com/qemu-devel@nongnu.org/msg668749.html And here is Jan's KVM Forum presentation on ivshmem v2: https://www.youtube.com/watch?v=3DTiZrngLUFMA Stefan