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[79.180.7.202]) by smtp.gmail.com with ESMTPSA id d72sm11876895qkg.102.2020.03.14.13.48.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 Mar 2020 13:48:16 -0700 (PDT) Date: Sat, 14 Mar 2020 16:48:11 -0400 From: "Michael S. Tsirkin" To: Nikita Leshenko Subject: Re: [PATCH v3 10/16] hw/i386/vmport: Add support for CMD_GETTIME Message-ID: <20200314162920-mutt-send-email-mst@kernel.org> References: <20200312195652-mutt-send-email-mst@kernel.org> <0bc7dac9-41a6-5af2-a1d5-ef1e79f92eea@oracle.com> <20200313113049-mutt-send-email-mst@kernel.org> <3c0d9308-f56c-0766-9815-241a28d9a246@oracle.com> <20200313170914-mutt-send-email-mst@kernel.org> <67d158f3-9d6c-cba8-6b3a-87702abdc6f0@oracle.com> <20200314151236-mutt-send-email-mst@kernel.org> <20200314152119-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 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: ehabkost@redhat.com, qemu-devel@nongnu.org, Liran Alon , pbonzini@redhat.com, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Sat, Mar 14, 2020 at 09:58:23PM +0200, Nikita Leshenko wrote: > I think that the reason that open-vm-tools doesn't move time backwards is= to > help applications that treat wallclock time as if it's monotonic time and= break > if the date is moved backwards (which may happen more frequently in virtu= al > environment so it's handled specifically). But this doesn't change the fa= ct that > this PV interface is for reporting wall time. > So I couldn't understand what > source other than gettimeofday() you were suggesting for Liran to use to = report > wallclock time. Some kind of offset to wallclock time I'm guessing. For example, we could save wall clock on vm save, and if it goes backwards on vm load, add an offset. --=20 MST