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Device trap has great impact on latency of real time (RT) tasks. This patch provide a virtio poll mode to avoid trap. According to the virtio spec, backend devices can declare the notification is not needed so that frontend will never trap. This means the backends make commitment to the frontends they have a poll mechanism which don’t need any frontends notification. This patch uses a periodic timer to give backends pseudo notifications so that drive them processing data in their virtqueues. People should choose a appropriate notification peroid interval to use this poll mode. Too big interval may cause virtqueue processing latency while too small interval may cause high SOS CPU usage. The suggested interval is between 100us to 1ms. The poll mode is not enabled by default and traditional trap notification mode will be used. To use poll mode for RT with interval 1ms. You can add following acrn-dm parameter. --virtio_poll 1000000 Tracked-On: #1956 Signed-off-by: Jie Deng <jie.deng@intel.com> Acked-by: Yu Wang <yu1.wang@intel.com>