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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 A5E57C433B4 for ; Tue, 4 May 2021 08:40:41 +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 4963361004 for ; Tue, 4 May 2021 08:40:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4963361004 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]:51716 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ldqbg-0002jd-Au for qemu-devel@archiver.kernel.org; Tue, 04 May 2021 04:40:40 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36430) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ldqZt-0001OT-5N for qemu-devel@nongnu.org; Tue, 04 May 2021 04:38:49 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:51601) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ldqZp-0005Dg-Af for qemu-devel@nongnu.org; Tue, 04 May 2021 04:38:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620117524; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=C+Q58dpgPacHikQSplFMBdjAR5od0VFE2VUEpdirUZA=; b=DZWc9kZnECxRRHh0waflN815KwNqg6g0Tbzl6VZTzdbh/7pLTnMGt5jMPlrk+exHCw53dO PKYva7wW6OwC3tI7lHMpxfRLr62mcMmo3RCuwRyJM+CN2+uA8c40Zi2Bvu8xOoiV+8WgCv cmeuLbvxvc43cO3oaJ1ChuzOBKufzPo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-301-EhycuRrgN-u-sLieJJy3Qg-1; Tue, 04 May 2021 04:38:33 -0400 X-MC-Unique: EhycuRrgN-u-sLieJJy3Qg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EC19E100A24D; Tue, 4 May 2021 08:38:31 +0000 (UTC) Received: from redhat.com (ovpn-113-37.ams2.redhat.com [10.36.113.37]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1A97C61156; Tue, 4 May 2021 08:38:28 +0000 (UTC) Date: Tue, 4 May 2021 09:38:25 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Pankaj Gupta Subject: Re: [PATCHv2 1/1] Support monitor chardev hotswap with QMP Message-ID: References: <20210413213459.629963-1-li.zhang@cloud.ionos.com> <875z0m4733.fsf@dusky.pond.sub.org> <87blad2v9x.fsf@dusky.pond.sub.org> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.0.6 (2021-03-06) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.698, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: QEMU , Markus Armbruster , Li Zhang , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Pankaj Gupta , Li Zhang Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, May 04, 2021 at 08:29:50AM +0200, Pankaj Gupta wrote: > +CC Danpb > > > >>> Marc-André, I'd like your opinion for this one, in particular the use of > > >>> g_source_remove(). > > >>> > > >> > > >> My opinion isn't really worth much, my review would have a bit more value. > > >> > > >> GSource has indeed some peculiar lifetime management, that I got wrong in > > >> the past. So I would be extra careful. > > >> > > >> But before spending time on review, I would also clarify the motivation > > >> and ask for testing. > > >> > > >> Markus, hot-adding/removing monitors isn't supported? > > >> > > >> > > > I realize you answered my question below. That's surprising me. Wouldn't it > > > make more sense to support it rather than having a pre-opened null-based > > > monitor that can have its chardev swapped? > > > > Yes, it would. Patches welcome. > > > > This patch is a somewhat ham-fisted and limited solution to the problem > > stated in the commit message. However, it might *also* be a reasonable > > improvement to chardev-change on its own. Not for me to judge. > > > > chardev-change comes with a number of restrictions. Let's have a closer > > look. It fails > > > > 1. when no such character device exists (d'oh) > > > > 2. for chardev-mux devices > > > > 3. in record/replay mode > > > > 4. when a backend is connected that doesn't implement the chr_be_change() > > method > > > > 5. when chr_be_change() fails > > > > 6. when creating the new chardev fails[*] > > > > Items 2, 3, 4 are restrictions. I figure 2 and 4 are simply not > > implemented, yet. I'm not sure about 3. > > > > Whether we want to accept patches lifting restrictions is up to the > > chardev maintainers. > > Maybe we can handle or already handle the restrictions at libvirt side? >From the libvirt side I'd just like to see the real problem addressed. ie actally implement monitor hotplug/unplug, instead of this hack where you pre-create a monitor with null backend. 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 :|