Release Notes PN 93000359G

Digi RealPort Linux
Version 1.6 Release 2

Software Package 40002086G

08/13/2003

Contents

  1. Introduction
  2. Supported Products
  3. Enhancements
  4. Bug Fixes
  5. Know Limitations
  6. Printers
  7. Ditty
  8. Configuration and Startup
  9. Documentation
  10. History

Introduction

Digi RealPort Linux is a driver package for Digi's Ethernet-based Serial Products. It is assumed that TCP/IP is running on the system and is properly configured. It is also useful, though not necessary, for the Wish package to be installed, or some other TCL interpreter, in order to use the RealPort Manager configuration tool.

Supported Linux Kernels

The driver package has been tested with the following unmodified Linux distributions:

Supported Products

Enhancements

Bug Fixes

Known Limitations

Printers

Transparent print now works, as of driver version 1.4.3 or higher.

Ditty

The ditty program provided with this package is named "ditty-rp" so as to not interfere with any other versions of ditty installed on the system (for use with other Digi products).

Configuration and Startup

There is a package of configuration tools provided that are, by default, located in the /usr/bin/dgrp/config directory. There are scripts for using the command line to add and remove products, as well as the RealPort Manager. This is essentially a graphical front end for the scripts and a visual tool for monitoring individual serial ports.

The software package includes two startup scripts in either the /etc/rc.d/init.d or /etc/init.d directories named "dgrp_daemon" and "dgrp_ditty". These scripts will be executed at startup automatically if the "chkconfig" tool is present on the system during the post installation phase of the driver install. Otherwise, these scripts must be manually added to the system startup.

To load and initialize the driver by hand, execute "dgrp_daemon start". To stop the driver daemons and unload the driver, execute "dgrp_daemon stop" followed by "rmmod dgrp".

Documentation

The following manpages are provided: ditty-rp(1), drpd(8), dgrp(8), dgrp_cfg_node(8), dgrp_gui(8).

RedHat 7.1 -- Kernel Compatibility Issues

Some 2.4 kernel-based distributions (RedHat 7.1 included) have a patch applied to them which modifies the behavior of Linux when an open of a serial port is canceled (for instance, if an application is waiting for the carrier signal and a user hits CTRL-C to kill the application).

With this behavior change, the device driver is unable to cleanup its internal data structures and the sane functioning of the driver is compromised. The classic symptom of this problem is that the command "lsmod", which (among other things) will return a count of the applications using the device driver, will return a non-zero value even if all applications associated with the serial ports are killed.

Unfortunately, it is impossible (from within the device driver) to determine which behavior is implemented in the running kernel. However, Digi now provides a workaround to allow customers with this problem to change the Digi behavior to be compatible with these "patched" kernels.

To enable the change which provides alternate behavior when a serial "open" call fails, execute the following after the device driver is loaded: 

echo "alt_fail_open=1" > /proc/dgrp/info

To return to the standard behavior, execute: 

echo "alt_fail_open=0" > /proc/dgrp/info

To examine the current state of this driver tuning variable: 

cat /proc/dgrp/info

Unfortunately, this command must be executed each time the device driver is loaded (i.e. when the system is booted). To make this process easier for customers, the Digi standard driver startup tools will execute the command on the customer's behalf when it loads the driver if the following command is executed: 

touch /usr/bin/dgrp/config/alt_fail_open

This command will create a file in your file system. The Digi tools, if they detect the existence of this file, will enable the "alt_fail_open" behavior on your behalf at every system boot.

History