Writing Device Drivers

Testing With a Serial Connection

Using a serial connection is a good way to test drivers. Use the tip(1) command to make a serial connection between a host system and a test system. With this approach, the tip window on the host console is used as the console of the test machine. See the tip(1) man page for additional information.

A tip window has the following advantages:

Note –

Although using a tip connection and a second machine are not required to debug a Solaris device driver, this technique is still recommended.

ProcedureTo Set Up the Host System for a tip Connection

  1. Connect the host system to the test machine using serial port A on both machines.

    This connection must be made with a null modem cable.

  2. On the host system, make sure there is an entry in /etc/remote for the connection. See the remote(4) man page for details.

    The terminal entry must match the serial port that is used. The Solaris operating system comes with the correct entry for serial port B, but a terminal entry must be added for serial port A:


    Note –

    The baud rate must be set to 9600.

  3. In a shell window on the host, run tip(1) and specify the name of the entry:

    % tip debug

    The shell window is now a tip window with a connection to the console of the test machine.

    Caution – Caution –

    Do not use STOP-A for SPARC machines or F1-A for x86 architecture machines on the host machine to stop the test machine. This action actually stops the host machine. To send a break to the test machine, type ~# in the tip window. Commands such as ~# are recognized only if these characters on first on the line. If the command has no effect, press either the Return key or Control-U.

Setting Up a Target System on the SPARC Platform

A quick way to set up the test machine on the SPARC platform is to unplug the keyboard before turning on the machine. The machine then automatically uses serial port A as the console.

Another way to set up the test machine is to use boot PROM commands to make serial port A the console. On the test machine, at the boot PROM ok prompt, direct console I/O to the serial line. To make the test machine always come up with serial port A as the console, set the environment variables: input-device and output-device.

Example 22–1 Setting input-device and output-device With Boot PROM Commands

ok setenv input-device ttya
ok setenv output-device ttya

The eeprom command can also be used to make serial port A the console. As superuser, execute the following commands to make the input-device and output-device parameters point to serial port A. The following example demonstrates the eeprom command.

Example 22–2 Setting input-device and output-device With the eeprom Command

# eeprom input-device=ttya
# eeprom output-device=ttya

The eeprom commands cause the console to be redirected to serial port A at each subsequent system boot.

Setting Up a Target System on the x86 Platform

On x86 platforms, use the eeprom command to make serial port A the console. This procedure is the same as the SPARC platform procedure. See Setting Up a Target System on the SPARC Platform. The eeprom command causes the console to switch to serial port A (COM1) during reboot.

Note –

x86 machines do not transfer console control to the tip connection until an early stage in the boot process unless the BIOS supports console redirection to a serial port. In SPARC machines, the tip connection maintains console control throughout the boot process.