From patchwork Thu Jan 14 23:46:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Igor Mammedov X-Patchwork-Id: 1426733 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=BAYwvIe1; dkim-atps=neutral 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 ozlabs.org (Postfix) with ESMTPS id 4DH1F82tQ8z9sVR for ; Fri, 15 Jan 2021 10:47:06 +1100 (AEDT) Received: from localhost ([::1]:37094 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l0CKU-00017u-SM for incoming@patchwork.ozlabs.org; Thu, 14 Jan 2021 18:47:02 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:42672) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l0CJu-00016W-5a for qemu-devel@nongnu.org; Thu, 14 Jan 2021 18:46:26 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:57980) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l0CJq-0000IZ-UR for qemu-devel@nongnu.org; Thu, 14 Jan 2021 18:46:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610667980; 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; bh=8Dspy5cp12GDiV3zu23e5jDiMyAfZz5XzDpKbWSyH6Q=; b=BAYwvIe1PsJPEwqzK3TlbY0T48bykDG22h8XmSqvql9MEQLWKjM8ucW+/vfwTZAN7XyuIS /ynXcBV/n26z8Q0nhRhhONKpseB+RDxCVUNsjyrNxXGC6vLzQEfvpkBYOAMfTrIzdGbW+R kYiruY4jPQ+4q0DBAmLvbGbmPba+o4o= 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-526-d_nkPxivPJ6yzpKyVVbwJw-1; Thu, 14 Jan 2021 18:46:18 -0500 X-MC-Unique: d_nkPxivPJ6yzpKyVVbwJw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A834C802B42 for ; Thu, 14 Jan 2021 23:46:17 +0000 (UTC) Received: from dell-r430-03.lab.eng.brq.redhat.com (dell-r430-03.lab.eng.brq.redhat.com [10.37.153.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id A5E2B19C45; Thu, 14 Jan 2021 23:46:16 +0000 (UTC) From: Igor Mammedov To: qemu-devel@nongnu.org Subject: [PATCH v2] machine: add missing doc for memory-backend option Date: Thu, 14 Jan 2021 18:46:12 -0500 Message-Id: <20210114234612.795621-1-imammedo@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=imammedo@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=63.128.21.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.248, 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: , Cc: mprivozn@redhat.com, pkrempa@redhat.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Add documentation for '-machine memory-backend' CLI option and how to use it. And document that x-use-canonical-path-for-ramblock-id, is considered to be stable to make sure it won't go away by accident. Signed-off-by: Igor Mammedov --- v2: - add doc that x-use-canonical-path-for-ramblock-id is considered stable, (Peter Krempa ) --- backends/hostmem.c | 10 ++++++++++ qemu-options.hx | 28 +++++++++++++++++++++++++++- 2 files changed, 37 insertions(+), 1 deletion(-) diff --git a/backends/hostmem.c b/backends/hostmem.c index 4bde00e8e7..6aaeefd0cf 100644 --- a/backends/hostmem.c +++ b/backends/hostmem.c @@ -497,6 +497,16 @@ host_memory_backend_class_init(ObjectClass *oc, void *data) host_memory_backend_get_share, host_memory_backend_set_share); object_class_property_set_description(oc, "share", "Mark the memory as private to QEMU or shared"); + /* + * Do not delete/rename option. This option must be considered stable + * (as if it didn't have the 'x-' prefix including deprecation period) as + * long as 4.0 and older machine types exists. + * Option will be used by upper layers to override (disable) canonical path + * for ramblock-id set by compat properties on old machine types ( <= 4.0), + * to keep migration working when backend is used for main RAM with + * -machine memory-backend= option (main RAM historically used prefix-less + * ramblock-id). + */ object_class_property_add_bool(oc, "x-use-canonical-path-for-ramblock-id", host_memory_backend_get_use_canonical_path, host_memory_backend_set_use_canonical_path); diff --git a/qemu-options.hx b/qemu-options.hx index 459c916d3d..22aa267c30 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -35,7 +35,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \ " suppress-vmdesc=on|off disables self-describing migration (default=off)\n" " nvdimm=on|off controls NVDIMM support (default=off)\n" " memory-encryption=@var{} memory encryption object to use (default=none)\n" - " hmat=on|off controls ACPI HMAT support (default=off)\n", + " hmat=on|off controls ACPI HMAT support (default=off)\n" + " memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n", QEMU_ARCH_ALL) SRST ``-machine [type=]name[,prop=value[,...]]`` @@ -96,6 +97,31 @@ SRST ``hmat=on|off`` Enables or disables ACPI Heterogeneous Memory Attribute Table (HMAT) support. The default is off. + + ``memory-backend='id'`` + An alternative to legacy ``-mem-path`` and ``mem-prealloc`` options. + Allows to use a memory backend as main RAM. + + For example: + :: + -object memory-backend-file,id=pc.ram,size=512M,mem-path=/hugetlbfs,prealloc=on,share=on + -machine memory-backend=pc.ram + -m 512M + + Migration compatibility note: + a) as backend id one shall use value of 'default-ram-id', advertised by + machine type (available via ``query-machines`` QMP command) + b) for machine types 4.0 and older, user shall + use ``x-use-canonical-path-for-ramblock-id=on`` backend option + (this option must be considered stable, as if it didn't have the 'x-' + prefix including deprecation period, as long as 4.0 and older machine + types exists), + if migration to/from old QEMU (<5.0) is expected. + For example: + :: + -object memory-backend-ram,id=pc.ram,size=512M,x-use-canonical-path-for-ramblock-id=on + -machine memory-backend=pc.ram + -m 512M ERST HXCOMM Deprecated by -machine