View source for KernelDebugRef - Symbol Files

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{{KernelDebugRef}}
The Kernel Debugger supports symbolic debugging. The MAPSYM utility program converts a ''.MAP'' file to a ''.SYM'' file. When a symbol file (generated with MAPSYM) is loaded by the operating system, the debugger can use public symbols in the operating system, executable programs, dynamic link libraries, or any device driver as part of an expression. The disassembler and the BL command also display addresses symbolically if the symbol exists for the address.

The debugger uses the MAPSYM format for the symbol file. The statement '''MAPSYM MAPFILE.MAP''' generates the ''.SYM'' file '''MAPFILE.SYM'''. The kernel's symbols must be on the system startup drive in the root directory, in a file named '''OS2KRNL.SYM'''. For device drivers, the ''.SYM'' file must be in the same directory as the device driver file with the ''.SYM'' extension.

To load symbols for a program or module, the ''.SYM'' file must be in the same directory as the ''.EXE'' or ''.DLL'' file, and the symbols will be loaded automatically.

The file name of the ''.SYM'' file must match that of the executable (program, device driver, or DLL) it corresponds to.

There can be more than one symbol file loaded at one time, and more than one currently active. The '''WA''', '''WR''', and '''LM''' commands control and list the currently active map files. The term ''map file'' refers to the ''.SYM'' file generated by MAPSYM. Each newly-loaded map file starts in the active state.

The message:

```Symbols Linked (xxxxxxxx)```

is printed when a symbol file loads successfully. The '''xxxxxxxx''' is the map name listed in the '''LM''' command.

The message:

```Symbols Unlinked (xxxxxxxxx)```

is printed when a program that has loaded symbols stops and the symbol file is removed.

Symbols are case insensitive.