Dbgp protocol

This page details the protocol used to communicate with SceDeci4pDbgp and SceDeci4pSDbgp from PSP2TMAPI.

PSP2TMAPI usage

PSP2TMAPI can be used from C++ or C#. See SCE samples and documentation for more details about PSP2TMAPI in general.

The following is sample C# code for sending and receiving custom protocol data:

using PSP2TMAPILib; //Include the PSP2 TM API library

const uint PROTOCOL_ID = 0x10020000; //SDbgp0
bool received_packet = false;

/* Receiving packets requires a helper class */
class PacketReceiver : IEventCustomProtocol {
        uint protocolId;
        bool receivedPacket = false;

        public PacketReceiver(uint proto) {
            protocolId = proto;
        }

        //Called every time a packet is received from the target
        public void OnPacketReceived(uint uProtocol, object Packet, uint uFragmentSeq, uint uAttributes) {
            if (uProtocol != protocolId)
                return;

            byte[] packetData = (byte[])Packet;
            string dataForPrint = "";
            foreach (byte b in packetData) {
                dataForPrint += string.Format("{0:X2} ", b);
            }
            Console.WriteLine("Got packet from protocol 0x{0:X}:", uProtocol);
            Console.WriteLine(dataForPrint);
            receivedPacket = true;
        }

        //Dummy routines for the rest of IEventCustomProtocol
        public void OnErrorInvalidHeader(uint uProtocol, object Packet) { }
        public void OnErrorNoConnection(uint uProtocol, object Packet) { }
        public void OnErrorNoProtocol(uint uProtocol, object Packet) { }
        public void OnErrorNoSpace(uint uProtocol, object Packet) { }
        public void OnStatusProtocol(uint uProtocol, uint uProtocolVersion, uint uProtocolLimit, uint uTargetNode, uint uStatus) { }
        public void OnStatusSpace() { }
        public void OnStatusForceUnregistered(uint uProtocol, string bstrRequester) { }
}

static void Main() {
  PSP2TMAPI api = new PSP2TMAPI();
  api.CheckCompatibility((uint)eCompatibleVersion.BuildVersion);

  //Select a target to interact with - this assumes target is already connected to
  ITarget target = api.Targets.DefaultTarget;

  try {
    target.ProtocolAvailabilityInfo(PROTOCOL_ID, out uint version, out uint versionLimit, out uint nodeID);
  } catch {
     //Protocol not available - cannot interact with (S)Dbgp (module probably not loaded)
     return;
  }

  //Make a receiver for the protocol
  PacketReceiver rcv = new PacketReceiver();

  //Register the protocol, register our receiver and send a packet
  target.RegisterCustomProtocol(PROTOCOL_ID);
  target.AdviseCustomProtocol(rcv);

  byte[] packet = new byte[4];
  packet[1] = 0xF0;
  packet[2] = 0x02;
  target.SendCustomProtocolData(protocol_id, packet);

  while (!rcv.receivedPacket) { /* wait for reply from target */ }

  //Cleanup
  target.UnadviseCustomProtocol(rcv);
  target.UnregisterCustomProtocol(PROTOCOL_ID);
}

Protocol IDs

SceDeci4pDbgp registers a single protocol for the whole system. SceDeci4pSDbgp registers a protocol for each CPU of the system (SDBGPx = CPU x).

Protocol name	ID
DBGP	0x00020000
SDBGP0	0x10020000
SDBGP1	0x10020001
SDBGP2	0x10020002
SDBGP3	0x10020003

Packets

Common

//Opaque header holding data for the transport protocol (?)
//This is only visible on Vita-side: on host side, PSP2TMAPI does not transmit this data
typedef struct _TransportHeader {
    uint8_t unknown[0x10];
} TransportHeader;

//Header for all packets
typedef struct _DbgpPacketHeader {
    TransportHeader OPAQUE;
    uint8_t direction; //<! 0 for Host->Target, 1 for Target->Host
    uint8_t group;     //<! Command group
    uint8_t type;      //<! Command type - group specific
    uint8_t unk13;     //<! Unknown. Maybe to serve as user-provided tag.
} DbgpPacketHeader;

//Header for Target->Host packets
typedef struct _DbgpT2HPacketHeader {
    DbgpPacketHeader hdr;
    uint8_t unk14;
    uint8_t unk15;
    uint16_t unk16;
    int32_t status; //<! Status/error code
} DbgpT2HPacket;

//Command groups
#define DBGP_GROUP_SYSTEM   (0x10u)
#define DBGP_GROUP_PROCESS  (0x20u)
#define DBGP_GROUP_THREAD   (0x30u)
#define DBGP_GROUP_MODULE   (0x40u)
#define DBGP_GROUP_unk_50   (0x50u)
#define DBGP_GROUP_FILE     (0x60u)
#define DBGP_GROUP_NET      (0x70u)
#define DBGP_GROUP_COREDUMP (0x80u)
#define DBGP_GROUP_unk_90   (0x90u) //DIP switch 0xD7 must be off
#define DBGP_GROUP_MISC     (0xF0u)

When a request is sent to target with type=X, the response is sent to host with type=X+1.

System Group

SYSTEM_GET_CONF

type	0x00
Dbgp availability:	Since at least firmware 0.920.050
SDbgp availability:	Since at least firmware 0.920.050

Obtain system configuration information.

/* Request packet: no data in addition to header */

/* Response packet for Dbgp: */
struct {
    DbgpT2HPacket hdr;
    uint32_t size;   //<! Size of the data starting from this field (0x1C)
    uint32_t unk20;  //<! Known values: 7 (0.920.050/4.00)
    uint32_t unk24;  //<! Known values: 0x100 (0.920.050/4.00)
    uint32_t unk28;  //<! Known values: 0 (0.920.050/4.00)
    uint32_t unk2C;  //<! Known values: 0 (0.920.050/4.00)
    uint32_t unk30;  //<! Known values: 0 (0.920.050), 3 (4.00)
    uint32_t fwVersion;
}

/* Response packet for SDbgp: */
struct {
    DbgpT2HPacket hdr;
    uint32_t size;  //<! Size of the data starting from this field (0x1C in 0.920.050, 0x30 in 4.00)
    uint32_t unk20; //<! Known values: 7 (4.00)
    uint32_t unk24; //<! Known values: 4 (0.920.050), 0x14 (4.00)
    uint32_t unk28; //<! Known values: 6 (0.920.050/4.00)
    uint32_t unk2C; //<! Known values: 0 (0.920.050/4.00)
    uint32_t unk30; //<! Known values: 1 (4.00), 4 (0.920.050)
    uint8_t unused_34[4];
    uint32_t fwVersion;
    uint8_t unused_3C[4];
    uint32_t aslrSeed;
    uintptr_t sysroot;    //<! Virtual address of the SceSysroot object
    uint32_t sysrootSize; //<! Size of the SceSysroot object
}

Group 0x50

This group is only valid for SDbgp, since at least firmware 0.920.050.

All packets of this group are silently ignored. No response is sent to the host.