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TLM Socket can not be inherited?

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I want to create a SystemC class as a derivative of another SystemC class like below:

struct A : public sc_module
    tlm_utils::multi_passthrough_target_socket<A, 32, tlm::tlm_base_protocol_types, 0, sc_core::SC_ZERO_OR_MORE_BOUND> tsocket;

struct B : public A

struct C : public sc_module


  tlm_utils::multi_passthrough_initiator_socket<C, 32, tlm::tlm_base_protocol_types, 0, sc_core::SC_ZERO_OR_MORE_BOUND> isocket;


Then I need to bind B to C

B b;

C c;


But, I will get some runtime error like below:

Error: (E120) sc_export instance has no interface: B.tsocket
In file: /home/tools/vcs/mx-2017.12-1/include/systemc231/sysc/communication/sc_export.h:162

Does SystemC do not support such a use case? Or I only need to do some “cast” to bind this socket? I'm not sure if it will bring some side-effect.

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You need to register callbacks to them so that they are bound to an interface. See Unbound multi_passthrough_initiator_socket/multi_passthrough_target_socket

In general I would discourage the use of them (or at least suggest to carefully think about their use) as they have several drawbacks: you cannot bind a target socket to a multi_passthrough_target_socket and you cannot bind in before_end_of_elaboration (see also Is there any order requirement for binding multi_passthrough_initiator_sockets?).


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  • 1 month later...
On ‎3‎/‎8‎/‎2019 at 3:22 AM, Philipp A Hartmann said:

From my understanding, the "before_end_of_elaboration" limitation got fixed in SystemC 2.3.1 (and a regression introduced by this was fixed in 2.3.2/2.3.3). 


Hi Philipp

I don't think it is fixed in either 2.3.2 or 2.3.3. The example below is still gives the error "Error: (E126) sc_export instance already bound: top_inst.middle_export_0" with both 2.3.2 and 2.3.3

#include "systemc.h"                                                                                                                  
#include "tlm_utils/multi_passthrough_initiator_socket.h"                                                                             
#include "tlm_utils/simple_target_socket.h"                                                                                           

struct top : sc_module {
    tlm_utils::multi_passthrough_initiator_socket<top> leaf{"leaf"};
    tlm_utils::multi_passthrough_initiator_socket<top> middle{"middle"};
    tlm_utils::simple_target_socket<top>  target{"target"};
    void before_end_of_elaboration(){

int sc_main(int argc, char** argv){
    top top_inst("top_inst");
    return 0;



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