Configuring the Debug Agent

The DebugAgent is activated by enabling the DEBUG_SYSTEM feature with the configurator(1CC) command:

% configurator -set DEBUG_SYSTEM=true

The DEBUG_SYSTEM feature is set to true by default.

When the DebugAgent is activated, communications on the serial line are performed in binary mode.

The DebugAgent has eight tunable options that you can configure with ews or configurator. The following three tunables control the behavior of the DebugAgent when it is enabled (DEBUG_SYSTEM=true):

• dbg.agent.startup specifies the behavior of the DebugAgent when the DebugServer attempts to connect to the target. Possible values are stop or resume. In stop mode the system will wait indefinitely until the DebugServer connects to the DebugAgent. In resume mode the system will wait for no more than one second. In both cases, the DebugAgent will issue the prompt DebugAgent: trying to sync with DebugServer... over the serial line and sound a beep. If the DebugServer does not connect, the system will continue booting and console operations will be performed raw, without any processing by the DebugAgent, on the serial line.

• dbg.agent.exceptmode specifies the behavior of the DebugAgent when an exception is raised before the DebugServer has connected. Possible values are catch or forward. In catch mode the DebugAgent catches all exceptions and blocks the target until a DebugServer has connected and resumed the execution of the target. In forward mode the DebugAgent forwards all exceptions directly to the kernel-installed handlers.

• dbg.agent.consolemode specifies the operating mode of the system console. Possible values are sync or async. In sync mode the target is blocked until each message has been transmitted to the host for output and acknowledged. In async mode, console output is buffered and transmitted to the host periodically, either when the buffer is full or on each timer interrupt, whichever occurs first.

The following five tunables control the serial line used by the DebugAgent.

• dbg.agent.device specifies the serial device used by the DebugAgent. Possible values are COM1, COM2, COM3, or COM4. COM1 refers to communication port 1 (COM 1) on a PC, or the first serial line on other boards. COM2 refers to communication port 2 (COM 2) on a PC, or the second serial line on other boards, and so on.

• dbg.agent.baud specifies the baud rate of the serial line. Possible values are: 115200, 57600, 38400, 19200, 9600, 4800, 2400, or 1200.

• dbg.agent.parity specifies the parity of the serial line. Possible values are none, even, or odd.

• dbg.agent.databits specifies the number of data bits. The only possible value is 8.

• dbg.agent.stopbits specifies the number of stop bits. Possible values are 1 or 2.

When the DebugAgent is not active (DEBUG_SYSTEM=false), the serial line is used by the system debugging console, and the five tunables control the serial device and speed.