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=-12.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 B07EBC433F5 for ; Wed, 22 Sep 2021 04:47:27 +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 281DA61050 for ; Wed, 22 Sep 2021 04:47:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 281DA61050 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:42912 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mSuAI-0004qT-4A for qemu-devel@archiver.kernel.org; Wed, 22 Sep 2021 00:47:26 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39666) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mSu9V-00044o-1v for qemu-devel@nongnu.org; Wed, 22 Sep 2021 00:46:39 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:35728) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mSu9T-00073W-EN for qemu-devel@nongnu.org; Wed, 22 Sep 2021 00:46:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632285993; 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=BUvjpj4VecKYZq87cYI3dJcc6ljbzVpji8Qs8a6sfFw=; b=MOA1nPj0A22QgKrEnOMEx/c7gy8e110icwidRXjUBh7+LrbnIUeYMVuxOI7YR+hjjbo46c xm4OjJAiVpMl5PGxqJo9oT8ll4baBeqFwtBdNC+C/FIbxSW2pvEvi20wanM6lHvgDar3Q3 g+AMzHLS9rTh6p7bLcnPLQ/Yt6y32m8= 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-37-MSKwRW9iPBu51V8PGGCYwg-1; Wed, 22 Sep 2021 00:46:29 -0400 X-MC-Unique: MSKwRW9iPBu51V8PGGCYwg-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 B19581006AA7; Wed, 22 Sep 2021 04:46:28 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-14.ams2.redhat.com [10.36.112.14]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 703F160C7F; Wed, 22 Sep 2021 04:46:28 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 0A1CB113865F; Wed, 22 Sep 2021 06:46:27 +0200 (CEST) From: Markus Armbruster To: Peter Maydell Subject: Re: ensuring a machine's buses have unique names References: <87czq0l2mn.fsf@dusky.pond.sub.org> Date: Wed, 22 Sep 2021 06:46:27 +0200 In-Reply-To: (Peter Maydell's message of "Tue, 14 Sep 2021 16:25:49 +0100") Message-ID: <87r1dhrzdo.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.475, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: , Cc: QEMU Developers , Philippe =?utf-8?Q?Mathieu-D?= =?utf-8?Q?aud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Peter Maydell writes: [...] > I'm not sure how best to sort this tangle out. We could: > * make controller devices pass in NULL as bus name; this > means that some bus names will change, which is an annoying > breakage but for these minor bus types we can probably > get away with it. This brings these buses into line with > how we've been handling uniqueness for ide and scsi. > * drop the 'name' argument for buses like ide that don't > actually have any callsites that need to pass a name > * split into foo_bus_new() and foo_bus_new_named() so that > the "easy default" doesn't pass a name, and there's at least > a place to put a doc comment explaining that the name passed > into the _named() version should be unique ?? > * something else ? A possible work-around for non-unique bus IDs is QOM paths. Precedence, kind of: commit 6287d827d494b5850049584c3f7fb1a589dbb1de Author: Daniel P. Berrang=C3=A9 Date: Fri Sep 11 13:33:56 2015 +0100 monitor: allow device_del to accept QOM paths =20 Currently device_del requires that the client provide the device short ID. device_add allows devices to be created without giving an ID, at which point there is no way to delete them with device_del. The QOM object path, however, provides an alternative way to identify the devices. =20 Allowing device_del to accept an object path ensures all devices are deletable regardless of whether they have an ID. =20 (qemu) device_add usb-mouse (qemu) qom-list /machine/peripheral-anon device[0] (child) type (string) (qemu) device_del /machine/peripheral-anon/device[0] =20 Devices are required to be marked as hotpluggable otherwise an error is raised =20 (qemu) device_del /machine/unattached/device[4] Device 'PIIX3' does not support hotplugging =20 Signed-off-by: Daniel P. Berrange Message-Id: <1441974836-17476-1-git-send-email-berrange@redhat.com> Reviewed-by: Eric Blake [Commit message touched up, accidental white-space change dropped] Signed-off-by: Markus Armbruster Their length makes QOM paths inconvenient for humans, but machines won't care. However, we already burned /-separated paths for paths within the qdev tree (the thing info qtree shows). Friends don't let friends use them (I should be able to dig up a critique if you're curious). Without that, it could be made to work like -device virtio-scsi,id=3Dvscsi -device scsi-cd,bus=3D/machine/peripheral/vscsi/virtio-backend/vscsi.0 We should consult with libvirt developers before we go down this route.