Debugging hints for diagnostic kernel extension

This topic provides examples and debugging hints for Diagnostic Kernel Extension.

Starting trace for diagnostic kernel extension
The Diagnostic Controller loads the Kernel Extensions for each device that requires it. This is specified by the PDiagRes->KernExt ODM stanza for the device. If using DIAGEX or PDIAGEX, there is a trace hook built in for debugging purposes.
Running trace for diagnostic kernel extension in the background
The Diagnostic Controller loads the Kernel Extensions for each device that requires it. This is specified by the PDiagRes->KernExt ODM stanza for the device. If you are using DIAGEX or PDIAGEX, there is a trace hook built in for debugging purposes.
Finding the right address
While in the Kernel Debugger, there is a structure that can be searched that gives the address of the trace buffer and first device handle. For DIAGEX, this structure is diag_cntl. For PDIAGEX, it is pdiag_cntl. Use the map command to get the address of the structure.
Looking at an illegal trap
In some instances, an Illegal Trap Instruction may occur if some application unloads their SLIH or kernel extension, without having previously unpinned its memory. This can also happen if the Diagnostic Kernel Extension close routine is not called on exit.

Parent topic: Diagnostic debugging hints