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[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) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: db020544-0d84-11ed-bd2d-47488cf2e6aa DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1658909977; 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=JO/xzLkPL1mgBIijC3VerS/zd8NHw9yAP7EwB/ihu59HI2z5Rk9raKc6zp8fC5XJaoiWoi 8tHIOw4ztDD0r0fNU8Dr41H2FstiFtHsK5T1G7AZGw0GkcavZN53GCTj3wbOA6Cfm8do94 PrG33k4y8dsfk2m/acf0FWmgbQNGc9c= X-MC-Unique: t_pY58LBOLGN__e3qCx1Ew-1 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=QMdN+Xwl62UYgBl1aVR863G0DVcRwPRCpfrTyRH2XKFW3hdA97/HPYwHMb0qoaMaIS Rm+NCRVPzv1I/iJKjL5OZ74+LMltEmuwgFP6pe7A8VfqWu56ZV8JCdfY9mOJ83F9TNf5 9Rjxrg9H2gpd3PDTlcf5zd8iO/w3eTUA81im+N8z2REt2Z6XUoHGstvjtkzZqhsQzf4t cil1ZtihrVZ69x2j1tBe8g/Vrm/HFAq1TxJUFxoodK42pQn/MptakgrQtsQKyvMoBger fAeYtBt46iOxWjOOGT0UdPB86gkGier6JjDfSQpxBcVNNxCm4W2+zohUNpDhkzHBapjT NtNA== X-Gm-Message-State: AJIora+Ew6gdlKjZr+Ay/BsTVTxAv+Au7++Ss92Lo25fqVUlBVkmDWSA cTVlm+NXusGDv8yUABq6xwVTKsFs2QhBhJCdkp8fJulOtw/offY4MwvTBlgN5cBsLm+kV9jEXZ/ qgZ/lsUThhdEzs7BaRwmfCpbzxcQ= X-Received: by 2002:a05:6402:354c:b0:43c:2cd0:49bc with SMTP id f12-20020a056402354c00b0043c2cd049bcmr10446058edd.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) 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 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 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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 >