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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 04FA0C636CC for ; Fri, 3 Feb 2023 07:01:04 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pNq3N-0005Qv-03; Fri, 03 Feb 2023 02:00:09 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pNq3I-0005Qd-AV for qemu-devel@nongnu.org; Fri, 03 Feb 2023 02:00:05 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pNq3F-0003uZ-Ua for qemu-devel@nongnu.org; Fri, 03 Feb 2023 02:00:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675407600; 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=14GBqWCt7wgfWtpwCrnMK8usthbOu1ASK+PivO2RZf4=; b=DJHVqYxJ4C/1WP+wtuH1aj1nGli6/lwvN3Jk66nK0AlwhKkpqONBZGa8slDOZi5xZxf5G8 awNhKERu0jnWytiElWFC7NNSMQ7EBlpTuLb4No5yNrUP5uZ8db+M1QANwvOlKToI5yDNAX cZOlhiORIw87PVIIZTHvJ2DdEfRMQoM= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-110-vrN4yY9APFyAp75X0vFI1w-1; Fri, 03 Feb 2023 01:59:56 -0500 X-MC-Unique: vrN4yY9APFyAp75X0vFI1w-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D7165811E6E; Fri, 3 Feb 2023 06:59:55 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.70]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A642A404CD80; Fri, 3 Feb 2023 06:59:55 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 232BB21E6A1F; Fri, 3 Feb 2023 07:59:54 +0100 (CET) From: Markus Armbruster To: Alexander Graf Cc: , Eduardo Habkost , "Daniel P . Berrange" , Eric Blake , Philippe Mathieu-Daude , Peter Xu , Paolo Bonzini , Igor Mammedov , David Hildenbrand , Stefan Hajnoczi , Ashish Kalra Subject: Re: [PATCH] hostmem-file: add offset option References: <20230202225603.27559-1-graf@amazon.com> Date: Fri, 03 Feb 2023 07:59:54 +0100 In-Reply-To: <20230202225603.27559-1-graf@amazon.com> (Alexander Graf's message of "Thu, 2 Feb 2023 22:56:03 +0000") Message-ID: <877cwzgro5.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Alexander Graf writes: > Add an option for hostmem-file to start the memory object at an offset > into the target file. This is useful if multiple memory objects reside > inside the same target file, such as a device node. > > In particular, it's useful to map guest memory directly into /dev/mem > for experimentation. > > Signed-off-by: Alexander Graf > --- [...] > diff --git a/qapi/qom.json b/qapi/qom.json > index 30e76653ad..d4e16c57a3 100644 > --- a/qapi/qom.json > +++ b/qapi/qom.json > @@ -649,6 +649,7 @@ > { 'struct': 'MemoryBackendFileProperties', > 'base': 'MemoryBackendProperties', > 'data': { '*align': 'size', > + '*offset': 'size', > '*discard-data': 'bool', > 'mem-path': 'str', > '*pmem': { 'type': 'bool', 'if': 'CONFIG_LIBPMEM' }, Looks like you forgot to document the new member. You may want to ... > diff --git a/qemu-options.hx b/qemu-options.hx > index d59d19704b..2f12a9299e 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -4875,7 +4875,7 @@ SRST > they are specified. Note that the 'id' property must be set. These > objects are placed in the '/objects' path. > > - ``-object memory-backend-file,id=id,size=size,mem-path=dir,share=on|off,discard-data=on|off,merge=on|off,dump=on|off,prealloc=on|off,host-nodes=host-nodes,policy=default|preferred|bind|interleave,align=align,readonly=on|off`` > + ``-object memory-backend-file,id=id,size=size,mem-path=dir,share=on|off,discard-data=on|off,merge=on|off,dump=on|off,prealloc=on|off,host-nodes=host-nodes,policy=default|preferred|bind|interleave,align=align,offset=offset,readonly=on|off`` > Creates a memory file backend object, which can be used to back > the guest RAM with huge pages. > > @@ -4945,6 +4945,10 @@ SRST > such cases, users can specify the required alignment via this > option. > > + The ``offset`` option specifies the offset into the target file > + that the region starts at. You can use this parameter to overload > + multiple regions into a single file. > + > The ``pmem`` option specifies whether the backing file specified > by ``mem-path`` is in host persistent memory that can be > accessed using the SNIA NVM programming model (e.g. Intel ... adapt the CLI documentation for it. [...]