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 D1089C19F29 for ; Wed, 27 Jul 2022 08:24:38 +0000 (UTC) Received: from localhost ([::1]:38594 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oGcLN-0003QH-Kg for qemu-devel@archiver.kernel.org; Wed, 27 Jul 2022 04:24:37 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54918) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oGcGh-0001SG-Cr for qemu-devel@nongnu.org; Wed, 27 Jul 2022 04:19:47 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:55737) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oGcGa-0000P1-2w for qemu-devel@nongnu.org; Wed, 27 Jul 2022 04:19:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1658909974; 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=ZuT/qe1DCcJGnSW38Ka6ZQWh4Y3+XNV+VTCNVSBHbvs=; b=dheGaqeEXE7TEVsm4BVsm530It1DjpS+QXi+w14GeLHPVpQs2vhjKpV5y2o3SqzGEjjAhX FoBe/8B0l8e2R7hkz0mnjLVyciEetbabzzAu5W3FqDvo9FLLX71hpSDxNzfzS69dUoWiWJ udupnvDnzPMpHFsqgHoA+vzabPvEO7U= Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-382-QI1ufbLZP6On_wnaQw40qg-1; Wed, 27 Jul 2022 04:19:33 -0400 X-MC-Unique: QI1ufbLZP6On_wnaQw40qg-1 Received: by mail-ed1-f70.google.com with SMTP id c9-20020a05640227c900b0043ad14b1fa0so10217984ede.1 for ; Wed, 27 Jul 2022 01:19:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ZuT/qe1DCcJGnSW38Ka6ZQWh4Y3+XNV+VTCNVSBHbvs=; b=qgJvmFJDEnz/LurexTFmEpAyCalnjMjgEwqp2RsbBk7C8ZHQu+fa1ecMjzjMKyvcXp V8nfpT+NJngG6GvGN2ROvNkOW4mUQe1r92t9rEV2AQDBDaWnm7jhAr2d6XHJoIGx+ypf ov6kwyZR+i5WMMRsRONn1lobgaUAAW5eQemAEbrSO7oPKMEzTe5F4xaYGytEnvg0pKXU k6AeV4pi65qMl0ZhJkoyBybnMnkF6xLMBEavhqEzW4vf2dtvi16JZkYmuLfYVxVzdo4S EsSR46PvKM5N/6+nLBn+xfg7Om5+/hUqiS788UrMslKMEqzizb5tmOSbJC8asBEu7DSo xxIA== X-Gm-Message-State: AJIora9essTtR7x/1SQ2RvkFeE+BK8g+aKKXb+KeK2mFpHNVO6RT9tfE sBwuu5jopCKDucbvthgI1U83+BtQP/iAVM2DHVMnOHmo8flg2lFo0hqwedDVmZlPhl2T05/55U8 0Pf1Y9ldZJLOSD3M= X-Received: by 2002:a05:6402:354c:b0:43c:2cd0:49bc with SMTP id f12-20020a056402354c00b0043c2cd049bcmr10446059edd.48.1658909972338; Wed, 27 Jul 2022 01:19:32 -0700 (PDT) X-Google-Smtp-Source: AGRyM1u1KG8ZK0GVys0wHa72IOIPmOKk2BY6xOgr/8AEf2x+4dmdaKNHM/PcWIuoPQ+mfc3SsNuwpw== X-Received: by 2002:a05:6402:354c:b0:43c:2cd0:49bc with SMTP id f12-20020a056402354c00b0043c2cd049bcmr10446040edd.48.1658909972039; Wed, 27 Jul 2022 01:19:32 -0700 (PDT) Received: from localhost (nat-pool-brq-t.redhat.com. [213.175.37.10]) by smtp.gmail.com with ESMTPSA id 11-20020a170906310b00b00722fc0779e3sm7213889ejx.85.2022.07.27.01.19.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Jul 2022 01:19:31 -0700 (PDT) Date: Wed, 27 Jul 2022 10:19:30 +0200 From: Igor Mammedov To: Huang Rui Cc: anthony.perard@citrix.com, qemu-devel@nongnu.org, xen-devel@lists.xenproject.org, Trigger Huang Subject: Re: Question to mem-path support at QEMU for Xen Message-ID: <20220727101930.66ed56e1@redhat.com> In-Reply-To: References: X-Mailer: Claws Mail 4.1.0 (GTK 3.24.34; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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" On Tue, 26 Jul 2022 15:27:07 +0800 Huang Rui wrote: > Hi Anthony and other Qemu/Xen guys, > > We are trying to enable venus on Xen virtualization platform. And we would > like to use the backend memory with memory-backend-memfd,id=mem1,size=4G > options on QEMU, however, the QEMU will tell us the "-mem-path" is not > supported with Xen. I verified the same function on KVM. > > qemu-system-i386: -mem-path not supported with Xen > > So may I know whether Xen has any limitation that support > memory-backend-memfd in QEMU or just implementation is not done yet? Currently Xen doesn't use guest RAM allocation the way the rest of accelerators do. (it has hacks in memory_region/ramblock API, that divert RAM allocation calls to Xen specific API) The sane way would extend Xen to accept RAM regions (whatever they are ram or fd based) QEMU allocates instead of going its own way. This way it could reuse all memory backends that QEMU provides for the rest of the non-Xen world. (not to mention that we could drop non trivial Xen hacks so that guest RAM handling would be consistent with other accelerators) > Looking forward to your reply! > > Thanks a lot, > Ray >