Memory system and operating method supporting fast boot using host memory buffer and default enabled information

A memory system comprising:

• a memory device capable of storing data;
• and
• a memory controller configured to communicate with the memory device to control the memory device,
• wherein the memory controller is configured to receive, from a host in communication with the memory system, default enabled information indicating whether the host maintains a configuration of a host memory buffer in the host and target data stored in the host memory buffer before shutdown of the memory system occurs and the memory system enters in a low power mode state,
• wherein the memory controller is further configured to:
• determine a target time which is a time point at which the memory system accesses the target data after waking up from the low power mode state as a time point at which a communication link between the host and the memory system is accessible when the host maintains the configuration of the host memory buffer and the target data stored in the host memory buffer.