From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 510F1606A31C for ; Thu, 12 Nov 2026 12:16:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=SMonIX9Q Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xRTiS-0007du-J8; Thu, 12 Nov 2026 07:15:44 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xRTiQ-0007bV-4t for qemu-devel@nongnu.org; Thu, 12 Nov 2026 07:15:42 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xRTiM-0002Qc-II for qemu-devel@nongnu.org; Thu, 12 Nov 2026 07:15:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1794485731; 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=5dvHlJJ2Aa3cqps97WEKkQYQyTCEljXU1znxuxPYkPE=; b=SMonIX9QmQXEmEfccQMyfr6t7b/hanHW2eN8ydUDWYk2gkBaqCol6Orgt/lQD91DzIgSjf 3aHtyUGZkzOiQLgepQwtomj2sTZ6iyDD9UxJve2lDnBRknrlZ4cYweXl8+fv1nMFDtEpVo mOp98bBWCl9anzEoddCXOp6mnV8XCS8= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-529-JD9bQ43RNoOG4aGckuXVDg-1; Thu, 12 Nov 2026 07:15:30 -0500 X-MC-Unique: JD9bQ43RNoOG4aGckuXVDg-1 X-Mimecast-MFC-AGG-ID: JD9bQ43RNoOG4aGckuXVDg_1794485729 Received: from mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.95]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id BAC35181AC82; Thu, 12 Nov 2026 12:15:28 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.7]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1B706343; Thu, 12 Nov 2026 12:15:28 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id B28A421E6A04; Thu, 12 Nov 2026 13:15:25 +0100 (CET) From: Markus Armbruster To: Markus Armbruster Cc: Daniel P. =?utf-8?Q?Berrang=C3=A9?= , qemu-devel@nongnu.org, David Hildenbrand , Igor Mammedov , Paolo Bonzini , Marcelo Tosatti , "Michael S. Tsirkin" , Richard Henderson , Thomas Huth , Jared Rossi , Edgar E. Iglesias Subject: Re: qemu-system-x86_64 appears to have sgx-epc, but not memory-backend-epc In-Reply-To: <87qzgu2i45.fsf@pond.sub.org> (Markus Armbruster's message of "Mon, 09 Nov 2026 15:29:30 +0100") References: <87zew5j3iv.fsf@pond.sub.org> <87qzgu2i45.fsf@pond.sub.org> Date: Thu, 12 Nov 2026 13:15:25 +0100 Message-ID: <87wlqiqm8y.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 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: 5 X-Spam_score: 0.5 X-Spam_bar: / X-Spam_report: (0.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Markus Armbruster writes: > Daniel P. Berrang=C3=A9 writes: [...] >> Normal practice is for types to be unconditionally registered. Do we >> have any examples outside of this SGX case where we conditionally >> register types ? Should we change this to follow normal practice ? > > Loosely related: conditional *class* properties. Example: > > static void > memfd_backend_class_init(ObjectClass *oc, const void *data) > { > HostMemoryBackendClass *bc =3D MEMORY_BACKEND_CLASS(oc); > > bc->alloc =3D memfd_backend_memory_alloc; > > if (qemu_memfd_check(MFD_HUGETLB)) { > object_class_property_add_bool(oc, "hugetlb", > memfd_backend_get_hugetlb, > memfd_backend_set_hugetlb); > object_class_property_set_description(oc, "hugetlb", > "Use huge pages"); > object_class_property_add(oc, "hugetlbsize", "uint64", > &uint64_type_info, > memfd_backend_get_hugetlbsize, > memfd_backend_set_hugetlbsize, > NULL, NULL); > object_class_property_set_description(oc, "hugetlbsize", > "Huge pages size (ex: 2= M, 1G)"); > } > > [...] > } > > These properties are also declared in qapi/qom.json if CONFIG_LINUX. > QAPI introspection (query-qmp-schema) shows them then. QOM > introspection (qom-list-properties etc.) only shows them when the > MFD_HUGETLB check succeeded. > > Feels undesirable to me. [...] Conditional turned out to be unnecessary here: Subject: [PATCH 7/7] backends/hostmem-memfd: Add huge TLB properties un= conditionally Date: Wed, 11 Nov 2026 13:23:42 +0100 Message-ID: <20261111122342.634370-8-armbru@redhat.com> I found a few more: * Property "loadparm" of scsi-cd, scsi-hd, virtio-blk-pci, virtio-net-pci only if target_s390x() * Several properties of xenpvh-machine on ARM and i386 only if ->has_virtio_mmio, ->has_pci, ->has_tpm I don't plan to examine these.