Entering a kernel debugger from a driver

If you are debugging a device driver or another part of the kernel, it is useful to force the debugger to be called at certain times. The following methods are available:

• DDI version 8 and later version drivers can use the call_demon(D3) function, which stops the kernel and calls the currently configured kernel debugger when the driver is compiled with the -DDEBUG flag. When the kernel debugger is exited, control returns to the caller.

• SCO OpenServer 5 drivers (ODDI version 3 and later) can use the calldebug(D3oddi) function, which stops the kernel and calls scodb when the driver is compiled under -DDEBUG mode. When the kernel debugger is exited, control returns to the caller.

• All DDI and ODDI drivers can also use the ASSERT(D3) function with CE_PANIC mode within -DDEBUG sections of code to check for certain conditions and, if appropriate, panic the system, which calls the currently-configured kernel debugger.

  Use the ASSERT(D3) function to check that the value of variables and structure members is correct at various stages of execution. ASSERT( ) evaluates a simple expression and, if it is not true, panics the system at that point so you can use a kernel debugger or the crash or crash(ADM) command to analyze the kernel. ASSERT( ) is ignored except when the driver is compiled with the -DDEBUG flag.