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([2001:b07:6468:f312:9520:22e6:6416:5c36]) by smtp.gmail.com with ESMTPSA id y5sm3904753wma.14.2019.09.25.04.24.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 25 Sep 2019 04:24:15 -0700 (PDT) Subject: Re: when to use virtio (was Re: [PATCH v4 0/8] Introduce the microvm machine type) To: David Hildenbrand , Sergio Lopez References: <20190924124433.96810-1-slp@redhat.com> <87h850ssnb.fsf@redhat.com> <231f9f20-ae88-c46b-44da-20b610420e0c@redhat.com> <77a157c4-5f43-5c70-981c-20e5a31a4dd1@redhat.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: <92063179-559b-6dd9-9ec6-2b4e3d924e66@redhat.com> Date: Wed, 25 Sep 2019 13:24:13 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 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: Pankaj Gupta , ehabkost@redhat.com, kvm@vger.kernel.org, mst@redhat.com, lersek@redhat.com, mtosatti@redhat.com, qemu-devel@nongnu.org, kraxel@redhat.com, imammedo@redhat.com, philmd@redhat.com, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 25/09/19 12:50, David Hildenbrand wrote: > Can't tell if there might be extensions (if virtio-mem ever comes to > life ;) ) that might make use of asynchronous communication. Especially, > there might be asynchronous/multiple guest->host requests at some point > (e.g., "I'm nearly out of memory, please send help"). Okay, this makes sense. I'm almost sold on it. :) Config space also makes sense, though what you really need is the config space interrupt, rather than config space per se. Paolo > So yes, currently we could live without the ring buffer. But the config > space and the virtqueue are real life-savers for me right now :)