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include vmm.inc
 
mov     eax, Message    ; system control message
mov     ebx, VM         ; VM handle (if needed by message)
mov     esi, Param1     ; message-specific parameter
mov     edi, Param2     ; message-specific parameter
mov     edx, Param3     ; message-specific parameter
VMMcall System_Control
 
jc      error           ; carry set if error
 
The System_Control service sends system control messages to all the virtual
devices and, depending on the message, to the VMM.
 
Parameter  Description
────────────────────────────────────────────────────────────────────────────
 
Message    Specifies the system control message. This parameter can be one
           of the following values:
 
           Value                   Meaning
           ─────────────────────────────────────────────────────────────────
           Begin_PM_App            A protected-mode application is starting
 
           Close_VM_Notify         A virtual machine is closing
 
           Create_VM               A virtual machine is being created
 
           Critical_Reboot_Notify  System is rebooting (interrupt disabled)
 
           Debug_Query             Requests for virtual device's debugging
                                   interface
 
           Destroy_VM              A virtual machine is being destroyed
 
           Device_Init             Virtual devices initializing (interrupts
                                   enabled)
 
           Device_Reboot_Notify    System is rebooting (interrupts enabled)
 
           End_PM_App              A protected-mode application is ending
 
           Init_Complete           All virtual devices have initialized
 
           Power_Event             Power is being suspended or resumed
 
           Reboot_Processor        Virtual device must reboot system if it
                                   can
 
           Set_Device_Focus        A virtual device is taking the focus
 
           Sys_Critical_Exit       System is terminating (interrupt
                                   disabled)
 
           Sys_Critical_Init       Virtual devices initializing (interrupts
                                   disabled)
 
           Sys_VM_Init             System VM is being created
 
           Sys_VM_Terminate        System VM is being destroyed
 
           System_Exit             System is terminating (interrupts
                                   enabled)
 
           VM_Critical_Init        Virtual machine being created (interrupts
                                   disabled)
 
           VM_Init                 Virtual machine being created (interrupts
                                   enabled)
 
           VM_Not_Executeable      Virtual machine being destroyed
 
           VM_Resume               Virtual machine execution resumed
 
           VM_Suspend              Virtual machine execution suspended
 
           VM_Terminate            Virtual machine begin destroyed
 
           For more information about these messages, see the individual
           message descriptions.
 
VM         Specifies a handle identifying a virtual machine. This parameter
           is not required by every system control message.
 
Param1     Specifies a message-specific parameter.
 
Param2     Specifies a message-specific parameter.
 
Param3     Specifies a message-specific parameter.
 
Return Value
 
The carry flag is clear if the service is successful. Otherwise, the carry
flag is set to indicate an error.
 
If the Create_VM message is successful, the EBX register contains the new
virtual machine handle.
 
Comments
 
Although virtual devices may receive many of the system control messages,
they may send only the following messages:
 
Message           Restructions
────────────────────────────────────────────────────────────────────────────
Create_VM         May only be sent by the virtual shell device.
 
Destroy_VM        May only be sent by the virtual shell device.
 
Set_Device_Focus  May be sent by any virtual device. If the device ID is
                  zero, all devices with settable focus must set their focus
                  to the specified virtual machine.
 
End_PM_App        May only be sent by the virtual MS-DOS manager.
 
Virtual devices must send and reply to messages correctly to prevent erratic
system behavior.
 
This service uses the ECX register, therefore the register cannot be used to
pass data through to the virtual device receiving the control message.
 
Uses
 
Flags, EBX if Create_VM
 
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