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=-3.6 required=3.0 tests=BAYES_00,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 6D047C433ED for ; Fri, 14 May 2021 11:30:06 +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 DAC0E61458 for ; Fri, 14 May 2021 11:30:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DAC0E61458 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]:58534 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lhW16-0005hN-Sq for qemu-devel@archiver.kernel.org; Fri, 14 May 2021 07:30:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47394) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lhW01-00050n-0P for qemu-devel@nongnu.org; Fri, 14 May 2021 07:28:57 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:51402) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lhVzx-00015X-H7 for qemu-devel@nongnu.org; Fri, 14 May 2021 07:28:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620991732; 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: in-reply-to:in-reply-to:references:references; bh=mQZqx0YDkhA3zX/9kBXj4jh4luXfmlEcEbZqPO4quEo=; b=VYDufVl5cFNQq1qv4IU0z8BPXeZbHSguPqtVBppPmT1OcBqPdb7FwNI7Py4CcJOqzS9w6Z a+8BsJqcF8ppdrAjMMz/CbH2pG8nJ7hwWCg6F8o4Xbd0gleA+EXkuzAx6S8FOVAn23AEZn YKWZEv5oEtJ8IjBdWSsaMriCv+COJMk= 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-574-um5NWk1CNMK7rrlllP5cTA-1; Fri, 14 May 2021 07:28:50 -0400 X-MC-Unique: um5NWk1CNMK7rrlllP5cTA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9D06E8015A8; Fri, 14 May 2021 11:28:47 +0000 (UTC) Received: from localhost (ovpn-114-20.ams2.redhat.com [10.36.114.20]) by smtp.corp.redhat.com (Postfix) with ESMTP id AEE4A6EF48; Fri, 14 May 2021 11:28:36 +0000 (UTC) Date: Fri, 14 May 2021 12:28:35 +0100 From: Stefan Hajnoczi To: Steven Sistare Subject: Re: [PATCH V3 07/22] cpr Message-ID: References: <1620390320-301716-1-git-send-email-steven.sistare@oracle.com> <1620390320-301716-8-git-send-email-steven.sistare@oracle.com> <008ac3a4-a187-3e9f-d82d-8279e82805b1@oracle.com> MIME-Version: 1.0 In-Reply-To: <008ac3a4-a187-3e9f-d82d-8279e82805b1@oracle.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="uAN+J7NCwWvVXUv5" Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@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=-0.699, 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: "Daniel P. Berrange" , "Michael S. Tsirkin" , Jason Zeng , Alex =?iso-8859-1?Q?Benn=E9e?= , Juan Quintela , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" , Alex Williamson , =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Paolo Bonzini , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , Markus Armbruster Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --uAN+J7NCwWvVXUv5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 13, 2021 at 04:21:02PM -0400, Steven Sistare wrote: > On 5/12/2021 12:19 PM, Stefan Hajnoczi wrote: > > On Fri, May 07, 2021 at 05:25:05AM -0700, Steve Sistare wrote: > >> To use the restart mode, qemu must be started with the memfd-alloc mac= hine > >> option. The memfd's are saved to the environment and kept open across= exec, > >> after which they are found from the environment and re-mmap'd. Hence = guest > >> ram is preserved in place, albeit with new virtual addresses in the qe= mu > >> process. The caller resumes the guest by calling cprload, which loads > >> state from the file. If the VM was running at cprsave time, then VM > >> execution resumes. cprsave supports any type of guest image and block > >> device, but the caller must not modify guest block devices between cpr= save > >> and cprload. > >=20 > > Does QEMU's existing -object memory-backend-file on tmpfs or hugetlbfs > > achieve the same thing? >=20 > Not quite. Various secondary anonymous memory objects are allocated via = ram_block_add > and must be preserved, such as these on x86_64. =20 > vga.vram > pc.ram > pc.bios > pc.rom > vga.rom > rom@etc/acpi/tables > rom@etc/table-loader > rom@etc/acpi/rsdp >=20 > Even the read-only areas must be preserved rather than recreated from fil= es in the updated > qemu, as their contents may have changed. Migration knows how to save/load these RAM blocks. Only pc.ram is significant in size so I'm not sure it's worth special-casing the others? Stefan --uAN+J7NCwWvVXUv5 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmCeXuMACgkQnKSrs4Gr c8jHywf8CxBROYscK92rOz9ibELAFk/j/tct/KiKBU1eHvvRqR1Ml6RhvCsdQ11P v7BdUw5a2J3CCaWkUDEikHEX5iEtRKJteRA4HR1BuJ3jU1s5hMfbQsk04ig+tTKi jjU4ZWtvFjFCn5HC4YP8F9MimzRLo1mk0glswka2V1wgQb4J/dEivk2WL+FXW7Qf nztB93Pu/iIsQ4yp7fOc2V0W6Htqr6+WXLjXe6AeCheT7he1W6fkuYry/xyCBc0x n0qVsefSl50HyerXTB61UAQpBZ/aQKpRar248iVtF8S0WN8wqWtcTH3nZ0/jbHBM X0Iagx64qufwtnlBKLdE7DVeQIqXOA== =nKP4 -----END PGP SIGNATURE----- --uAN+J7NCwWvVXUv5--