Sample VxD Code

This collection of programs demonstrates one way a VxD can cause a message
to be posted to a Windows application.  This example also shows a fairly
useful implementation of real and protected mode APIs.

Uses the following services:
         VMMCall _Allocate_Device_CB_Area
         VMMCall Fatal_Memory_Error
         VMMCall Get_Sys_VM_Handle
         VMMCall Test_Sys_VM_Handle      
         VMMCall Get_Crit_Section_Status 
         VMMCall Call_When_VM_Ints_Enabled
         VMMCall Call_Priority_VM_Event
         VMMCall Begin_Nest_Exec
         VMMCall Simulate_Push
         VMMCall Simulate_Far_Call
         VMMCall Resume_Exec
         VMMCall End_Nest_Exec

This VxD can be used to monitor the activity associated with a particular
hardware interrupt (IRQ). Specifically, hardware interrupts, EOIs, IRETs,
virtual interrupts, and mask changes associated with a particular IRQ
will trigger debugging output on the secondary monitor of the system.  
Note that you must have a secondary monitor to use this VxD.

Uses the following services:
         VMMCall Get_Profile_Decimal_Int   
         VMMCall Clear_Mono_Screen
         VMMCall Set_Mono_Cur_Pos
         VMMCall Out_Mono_String

         VxDCall VPICD_Virtualize_IRQ
         VxDCall VPICD_Set_Int_Request
         VxDCall VPICD_Clear_Int_Request
         VxDCall VPICD_Phys_EOI

This VxD can be used to monitor the I/O traffic associated with a particular
device. Specifically, IN's and OUT's to a single I/O port will trigger 
debugging output on the secondary monitor of the system.  Note that you 
must have a secondary monitor to use this VxD.

Uses the following services:
         VMMCall Install_IO_Handler
         VMMCall Get_Profile_Hex_Int       
         VMMCall Clear_Mono_Screen
         VMMCall Set_Mono_Cur_Pos
         VMMCall Out_Mono_String

This VxD demonstrates how to use the Call_When_Idle function.

Uses the following services:
         VMMCall Call_When_Idle

The purpose of this sample VxD is to demonstrate the basic use of the 
Install_IO_Handler and Shell_Resolve_Contention function calls. The 
Install_IO_Handler call enables this VxD to trap IN and OUT's to a port
from any VM.  The Shell_Resolve_Contention call is then used to display a
dialog box when another VM attempts to use a port that is already assigned 
to another VM.

This VxD also demonstrates the use of Enable_Local_Trapping and 
Disable_Local_Trapping to allow the owner of the port in question to 
freely do I/O to the port without overhead.

Uses the following services:
         VMMCall Install_IO_Handler
         VMMCall Enable_Local_Trapping 
         VMMCall Disable_Local_Trapping
         VxDCall Shell_Resolve_Contention
         

This VxD uses the Hook_PM_Fault to catch GP faults.  When this VxD receives
control because of a GP fault, it will execute an INT 1.  If execution is
continued, control is passed to the next handler in the fault handler chain.

The "VxDStub" code for this VxD is an example in itself.  The stub hooks
INT 2Fh then terminates with stay resident.  When Windows later loads,
this TSR responds to the INT 2Fh, AX=1605h (Windows initialization)
broadcast.  The TSR returns a structure that will cause the VxD to be loaded.
Thus, no "device=" line is required in the SYSTEM.INI file.

Uses the following services:
         VMMCall Hook_PM_Fault
         

The basic structure of a VxD is illustrated by this VxD. As written, 
it can be loaded although it performs no function. This VxD can be 
used as a base set of source files to start a VxD project. 

Documentation

Utilities