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 B13FEC7618D for ; Tue, 4 Apr 2023 06:49:54 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pjaTs-0004db-BE; Tue, 04 Apr 2023 02:49:24 -0400 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 1pjaTn-0004d0-Qm for qemu-devel@nongnu.org; Tue, 04 Apr 2023 02:49:20 -0400 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 1pjaT8-0002Xp-Lz for qemu-devel@nongnu.org; Tue, 04 Apr 2023 02:49:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680590917; 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=v3CORH+sBL1yduy3gQjrX81ua0rFJGHlL8JvXRt3dKw=; b=C5JjfOLoG8aKcw8j+yJsTb45RWl2hD7lMPcJTpCEwmuYRV2v5pa1rB6gkiUyRtRUYLDxHJ /yj6f8KqtPIpmdBPrBDFoAgw5YrBRE8xmHxTqxtj2byc/HH5qkoJ+nZ1orz4Pg+2gKNbag mnlL6A3Nbhf5GLFQqwCHVko/RVM0whU= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-414-tTVjKliRNzqnZ_pk2fdgow-1; Tue, 04 Apr 2023 02:48:33 -0400 X-MC-Unique: tTVjKliRNzqnZ_pk2fdgow-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5CF263C0D856; Tue, 4 Apr 2023 06:48:33 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.52]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1C9142166B26; Tue, 4 Apr 2023 06:48:33 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id E7F7F21E6926; Tue, 4 Apr 2023 08:48:31 +0200 (CEST) From: Markus Armbruster To: Alexander Graf Cc: , David Hildenbrand , Markus Armbruster , Eduardo Habkost , "Daniel P . Berrange" , Eric Blake , "Philippe Mathieu-Daude" , Peter Xu , "Paolo Bonzini" , Igor Mammedov , "Stefan Hajnoczi" , Ashish Kalra , "Tom Lendacky" Subject: Re: [PATCH v5] hostmem-file: add offset option References: <20230403221421.60877-1-graf@amazon.com> Date: Tue, 04 Apr 2023 08:48:31 +0200 In-Reply-To: <20230403221421.60877-1-graf@amazon.com> (Alexander Graf's message of "Mon, 3 Apr 2023 22:14:21 +0000") Message-ID: <878rf82lds.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 10.11.54.6 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. > > To make this work consistently, also fix up all places in QEMU that > expect fd offsets to be 0. > > Signed-off-by: Alexander Graf [...] > diff --git a/qapi/qom.json b/qapi/qom.json > index a877b879b9..f740f74be3 100644 > --- a/qapi/qom.json > +++ b/qapi/qom.json > @@ -635,6 +635,10 @@ > # specify the required alignment via this option. > # 0 selects a default alignment (currently the page size). (default: 0) > # > +# @offset: the offset into the target file that the region starts at. You can > +# use this option to back multiple regions with a single file. Must be > +# a multiple of the page size. (default: 0) (since 8.1) > +# > # @discard-data: if true, the file contents can be destroyed when QEMU exits, > # to avoid unnecessarily flushing data to the backing file. Note > # that ``discard-data`` is only an optimization, and QEMU might > @@ -655,6 +659,7 @@ > { 'struct': 'MemoryBackendFileProperties', > 'base': 'MemoryBackendProperties', > 'data': { '*align': 'size', > + '*offset': 'size', > '*discard-data': 'bool', > 'mem-path': 'str', > '*pmem': { 'type': 'bool', 'if': 'CONFIG_LIBPMEM' }, Acked-by: Markus Armbruster [...]