aoc compile error: using host channel feature

Hi,

I am writing a simple OpenCL code for testing host channel feature introduced 17.1.

The code is as follows:

# pragma OPENCL EXTENSION cl_intel_fpga_host_pipe : enable
kernel void clkernel(
       __attribute__((intel_host_accessible)) __read_only pipe ulong4 cl_input,
       __attribute__((intel_host_accessible)) __write_only pipe ulong4 cl_output) {
  ulong4 val;
  while( 1 ) {
    if( read_pipe(cl_input, &val)) {
      while( !write_pipe(cl_output, &val) ) ;
    }
  }
}

when compiling the code by aoc, error message was printed like this.

$ which aoc

/cad/intelFPGA/17.1/hld/bin/aoc

$ aoc clkernel.cl

aoc: Running OpenCL parser....

clkernel.cl:1:26: warning: unknown OpenCL extension 'cl_intel_fpga_host_pipe' - ignoring# pragma OPENCL EXTENSION cl_intel_fpga_host_pipe : enable

^

1 warning generated.

aoc: Optimizing and doing static analysis of code...

Error: Channel has no point connection: ID= host_to_dev

avm_channel_id_host_to_dev_read connection missing, or optimized away

Error: Could not write system script to file. System generation aborted!

Error: System integrator FAILED.

Refer to clkernel/clkernel.log for details.

What should I do next?