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=-0.6 required=3.0 tests=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 1C77DC432C0 for ; Fri, 29 Nov 2019 20:09:07 +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 D78A621736 for ; Fri, 29 Nov 2019 20:09:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BLKNVBBj" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D78A621736 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]:34942 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iamZd-0004hV-28 for qemu-devel@archiver.kernel.org; Fri, 29 Nov 2019 15:09:05 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:32947) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iamWk-0003C0-8D for qemu-devel@nongnu.org; Fri, 29 Nov 2019 15:06:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iamWd-0008C3-Qb for qemu-devel@nongnu.org; Fri, 29 Nov 2019 15:06:02 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:59584 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iamWd-0007yo-MR for qemu-devel@nongnu.org; Fri, 29 Nov 2019 15:05:59 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1575057953; h=from:from: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=z2BH+ncZhIdQhEhHBDLTr3O2l5UNSWa/LVXLIyALssw=; b=BLKNVBBjHsVHuj/i/ZAGL9s0GQsA3PtkzsZjNOTikOozf0/ZvKlxS4tTKYZjPE4CWt/vNj LG2ct258Kzdu2D7SENQJGWMYO9Nqs37MyLI2V/YWF2hwBM4r2ZgFe07Y8RCHQXSvhYc5qa Lyu5TjdrHI0S7zt2pBB7aDM8MFxLzHk= 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-39-ayszhi_BM4i-BYxjkg_prA-1; Fri, 29 Nov 2019 15:05:52 -0500 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id AB79A18543A0; Fri, 29 Nov 2019 20:05:50 +0000 (UTC) Received: from localhost (ovpn-116-90.gru2.redhat.com [10.97.116.90]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9AF7F600C4; Fri, 29 Nov 2019 20:05:47 +0000 (UTC) Date: Fri, 29 Nov 2019 17:05:45 -0300 From: Eduardo Habkost To: Peter Maydell Subject: Re: qom device lifecycle interaction with hotplug/hotunplug ? Message-ID: <20191129200545.GG14595@habkost.net> References: <20191128182705.0635d1d4@redhat.com> <20191129132641.4c7da6c5@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: ayszhi_BM4i-BYxjkg_prA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 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: Damien Hedde , Igor Mammedov , QEMU Developers , Stefan Hajnoczi , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Nov 29, 2019 at 12:45:09PM +0000, Peter Maydell wrote: > On Fri, 29 Nov 2019 at 12:26, Igor Mammedov wrote: > > But from the my very limited understanding, on real hardware, > > once device is uplugged it's gone (finalized) from machine > > perspective, so it's unclear to my why someone would use > > realize->unrealize->realize hotplug scenario. >=20 > Well, on real hardware 'unplug' is different from 'unrealize'. > So I think for QEMU if we wanted to allow this sort of 'unplug > and replug the same device' we should do it by: >=20 > instance_init -> realize -> plug -> unplug -> plug -> unplug -> > unrealize -> finalize >=20 > So unrealize/finalize is when the device is actually destroyed, > and if you're going to replug the device you don't destroy it > on unplug. So, to summarize the current issues: 1) realize triggers a plug operation implicitly. 2) unplug triggers unrealize implicitly. Do you expect to see use cases that will require us to implement realize-without-plug? Similarly, do you expect use cases that will require us to implement unplug-without-unrealize? --=20 Eduardo