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([2001:b07:6468:f312:e95f:9718:ec18:4c46]) by smtp.gmail.com with ESMTPSA id c11sm479934wmb.45.2020.07.07.03.54.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 07 Jul 2020 03:54:32 -0700 (PDT) Subject: Re: [PATCH 2/2] hyperv/synic: Allocate as ram_device To: Vitaly Kuznetsov References: <20200108135353.75471-1-dgilbert@redhat.com> <20200108135353.75471-3-dgilbert@redhat.com> <20200109064527-mutt-send-email-mst@kernel.org> <20200109120820.GB6795@work-vm> <20200109071454-mutt-send-email-mst@kernel.org> <20200109122237.GD6795@work-vm> <20200109080412-mutt-send-email-mst@kernel.org> <20200109132242.GF6795@work-vm> <3162676e-da40-7a3f-1777-2ed4f3efffe1@redhat.com> <87h814r639.fsf@vitty.brq.redhat.com> From: Paolo Bonzini Message-ID: <57b450ab-313d-5582-0ba9-43c1de0c9e75@redhat.com> Date: Tue, 7 Jul 2020 12:54:31 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <87h814r639.fsf@vitty.brq.redhat.com> Content-Language: en-US Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=205.139.110.61; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/07 00:31:00 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action 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: Roman Kagan , jasowang@redhat.com, "Michael S. Tsirkin" , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 09/01/20 16:40, Vitaly Kuznetsov wrote: >>>>> Do we want a new memory_region_init for that or just to be able to add >>>>> a flag? >>>>> >>>> I think a flag API is preferable since this can apply to any kind of >>>> region. But can go either way, Paolo's the maintainer there. >>> (Copying Paolo in) >>> So what exactly does this flag mean; to me it's 'no vhost' - but is it >>> actually more general? >> It has two more effects in addition to no vhost: >> >> 1) it is skipped when dumping the guest (is this a good or bad idea for >> SynIC?) > Imagine we have an not yet consumed message sitting in message page, or > a signalled event, do I understand correctly that these are going to get > lost upon migration? This may not work then -- unless we transfer > in-QEMU synic state somehow separately. (Thread necromancy). This is just dumping (and it should probably be extended to core dumping, i.e. MADV_DONTDUMP). Migration is controlled separately with vmstate_register_ram. Paolo