Filename and line number information is stored inside private symbols (.pdb file). So if private symbols are available the debugger will try figuring out the line number information. Note: public symbols doesn’t have line number information.
So the question I’ve heard people new to windbg ask is how to turn off line number display. What’s the command for this. What I normally do is and the easiest of all is the ‘.lines’ command. This is a toggle command, next time you execute .lines, the command will turn ‘on’ line number information.
Another option is to use .symopt command:
The symbol option of interest to us is: SYMOPT_LOAD_LINES. Following is the MSDN description of this item.
This symbol option allows line number information to be read from source files. This option must be on for source debugging to work correctly.
In KD and CDB, this option is off by default; in WinDbg, this option is on by default. In CDB and KD, the -lines command-line option will turn this option on. Once the debugger is running, it can be turned on or off by using .symopt+0x10 or .symopt-0x10, respectively. It can also be toggled on and off by using the .lines (Toggle Source Line Support) command.
This option is on by default in DBH. Once DBH is running, it can be turned on or off by using symopt +10 or symopt -10, respectively.