How to enable debug prints in IEEE 1394 drivers

The Institute of Electrical and Electronics Engineers (IEEE) 1394 drivers, 1394Bus.sys and Ohci1394.sys, print debug messages to the kernel debugger depending upon the current debug level. By enabling debug message printing, you can see all the debug messages that are being printed by the driver. These debug messages are very useful for developers who are building their driver or application around the 1394 drivers.

The current debug level is stored in a global variable that is defined in the respective driver. This value must be changed in order to see the debug messages. By default, this value is set to 0 (zero) and can be increased to a larger value. Larger values result in more verbose messages.

The debug message is available only in checked build binaries. The checked build version of Windows 2000 should be used to get the debug messages. To get the debug messages in the retail build of Windows 2000, replace the 1394Bus.sys and Ohci1394.sys files with checked build binaries. Also, the symbols are required in the host computer to change the debug level.

Changing the Debug Level for 1394Bus.sys

This can be done by typing the following command in the kernel debugger: This will print the current value and prompt for a new value as follows: Type the new value, and then press ENTER for the next value. The command sets the new debug level to 2.

Changing the Debug Level for Ohci1394.sys

This can be done by typing the following command in the kernel debugger: This will print the current value and prompt for a new value as follows: Type the new value, and then press ENTER for the next value. The command sets the new debug level to 2.

When you change the value, the following error message may appear: Or, instead of printing the current value, question marks are printed, as follows: This happens when the expression evaluator is set to the wrong type. To change this, type the following command: To check the current setting of the expression evaluator, use the following command: This command displays either "MasmEval off" or "MasmEval on", which indicates the state of expression evaluator.