src/dev/net/dist_packet.hh

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/* @file
 * Header packet class for dist-gem5 runs.
 *
 * For a high level description about dist-gem5 see comments in
 * header file dist_iface.hh.
 *
 * The DistHeaderPkt class defines the format of message headers
 * sent among gem5 processes during a dist gem5 simulation. A header packet
 * can either carry the description of data packet (i.e. a simulated Ethernet
 * packet) or a synchronisation related control command. In case of
 * data packet description, the corresponding data packet always follows
 * the header packet back-to-back.
 */
#ifndef __DEV_DIST_PACKET_HH__
#define __DEV_DIST_PACKET_HH__

#include <cstring>

#include "base/types.hh"

namespace gem5
{

class DistHeaderPkt
{
  private:
    DistHeaderPkt() {}
    ~DistHeaderPkt() {}

  public:
    enum class ReqType { immediate, collective, pending, none };
    /**
     *  The msg type defines what information a dist header packet carries.
     */
    enum class MsgType
    {
        dataDescriptor,
        cmdSyncReq,
        cmdSyncAck,
        unknown
    };

    struct Header
    {
        /**
         * The msg type field is valid for all header packets.
         *
         * @note senderRank is used with data packets while collFlags are used
         * by sync ack messages to trigger collective ckpt or exit events.
         */
        MsgType msgType;
        Tick sendTick;
        /**
         * Length used for modeling timing in the simulator.
         * (from EthPacketData::simLength).
         */
        unsigned simLength;
        union
        {
            Tick sendDelay;
            Tick syncRepeat;
        };
        union
        {
            /**
             * Actual length of the simulated Ethernet packet.
             * (from EthPacketData::length).
             */
            unsigned dataPacketLength;
            struct
            {
                ReqType needCkpt;
                ReqType needStopSync;
                ReqType needExit;
            };
        };
    };
};

} // namespace gem5

#endif // __DEV_DIST_PACKET_HH__