[VTA] tvm.rpc.server.start is not called

[minils]

When running the script python vta/tests/python/pynq/test_program_rpc.py, the function tvm.rpc.server.startis never called on the target (PYNQ in my case) which leads to an AttributeError: Module has no function 'tvm.contrib.vta.init' because the function is not registered (see vta/python/vta/exec/rpc_server.py:65).

The function should be called at src/runtime/rpc/rpc_endpoint.cc:728

void RPCEndpoint::ServerLoop() {                                                                                    
  if (const auto* f = Registry::Get("tvm.rpc.server.start")) {                                                      
    (*f)();                                                                                                         
  }                                                                                                                 
  TVMRetValue rv;                                                                                                   
  ICHECK(HandleUntilReturnEvent(false, [](TVMArgs) {}) == RPCCode::kShutdown);                                      
  if (const auto* f = Registry::Get("tvm.rpc.server.shutdown")) {                                                   
    (*f)();                                                                                                         
  }                                                                                                                 
  channel_.reset(nullptr);                                                                                          
}

But the ServerLoop is also not called. Not sure why...

[minils]

Also see this thread

[tqchen]

THanks @minils for reporting. This is likely due to our recent update to rpc server and results the requirement of the function to be registered within the rpc server launch.

[tqchen]

Please see if #8604 fixes the problem

[minils]

Thanks @tqchen for looking into this.
Running the rpc server now gives another error:

xilinx@pynq:~/tvm$ sudo ./apps/vta_rpc/start_rpc_server.sh
Traceback (most recent call last):
  File "/usr/lib/python3.6/runpy.py", line 183, in _run_module_as_main
    mod_name, mod_spec, code = _get_module_details(mod_name, _Error)
  File "/usr/lib/python3.6/runpy.py", line 109, in _get_module_details
    __import__(pkg_name)
  File "/home/xilinx/tvm/vta/python/vta/__init__.py", line 25, in <module>
    from .autotvm import module_loader
  File "/home/xilinx/tvm/vta/python/vta/autotvm.py", line 21, in <module>
    from . import rpc_client
  File "/home/xilinx/tvm/vta/python/vta/rpc_client.py", line 22, in <module>
    from .environment import get_env
  File "/home/xilinx/tvm/vta/python/vta/environment.py", line 296, in <module>
    @register_intrin_lowering("tir.vta.coproc_sync", "default")
  File "/home/xilinx/tvm/python/tvm/ir/op.py", line 223, in _register
    _ffi_api.RegisterOpLowerIntrinsic(op_name, f, target, level)
AttributeError: module 'tvm.ir._ffi_api' has no attribute 'RegisterOpLowerIntrinsic'

I could previously fix this error by moving some functions from vta/python/vta/environment.py to vta/python/vta/build_module.py (see fix.patch). But with the latest commits from main it doesn't work any more.

[tqchen]

Thanks for the note, please see if #8671 fixes the problem

[Lunderberg]

Closing, can be re-opened if issue is still occurring.