Why does $$parms show value as "?"

[Grant Edwards]

Here's the function in the module I'm debugging:

  int xmit_packet(struct sk_buff *skb)
  {
    return dev_queue_xmit(skb);
  }

Here's my systemtap script:

  probe begin
  {
      print("systemtap begin\n");
  }
  
  probe module("nslink").function("xmit_packet")
  {
      printf("%s\n",$$parms);
  }
  
  probe end
  {
      print("systemtap end\n");
  }


And here's what happens when I run it:

  # stap transmit.stp 
  systemtap begin
  skb=?
  skb=?
  skb=?
  skb=?
  skb=?
  skb=?
  skb=?
  skb=?
  skb=?
  skb=?
  ^Csystemtap end
  # 

Why isn't systemtap printing the value of the parameter "skb"?

The module in question is built "out of tree" and then installed in 
/lib/modules/VERSION/misc, and according to "file" it's not stripped.

-- 
Grant Edwards               grant.b.edwards        Yow! I didn't order any
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