A question about gnumach...

[Diego Roversi]

Hello,

  I was studing the gnumach sources and I found the following interface:
  
routine device_read(
                device          : device_t;
        sreplyport reply_port   : reply_port_t;
        in      mode            : dev_mode_t;
        in      recnum          : recnum_t;
        in      bytes_wanted    : int;
        out     data            : io_buf_ptr_t
        );

But I don't understand why there are two arguments: recnum and bytes_wanted.
Only one of them is not enough? There is some documentation somewhere about
this system call?

TIA

--- 
Saluti / Regards

Diego Roversi | diegor at maganet.net
              | diegor at tiscalinet.it