Power_Event

include vmm.inc
include power.inc

mov     esi, Event
mov     edi, OFFSET32 Return
mov     eax, Power_Event
VMMCall System_Control
 

Notifies the virtual device that a power event has just occurred. The virtual device may modify all general registers and flags.

• The virtual device must return with carry clear, even to fail the call. See the description of Return for information on how to fail the call.

Event

Type of power event. Can be one of these values:

Value	Meaning
PWR_CRITICALRESUME	Resume critical operations after suspension.
PWR_SUSPENDREQUEST	Suspend operation.
PWR_SUSPENDRESUME	Resume operation after suspension.

Return

Address of the doubleword that receives the return value, which can be one of these values:

Value	Meaning
PWR_FAIL	Virtual device failed to process the event.
PWR_OK	Virtual device processed the event successfully.

All other values are reserved.

To fail the call, a virtual device should store the value PWR_FAIL in the doubleword pointed to by Return. For the call to succeed, the virtual device must leave the doubleword pointed to by Return unchanged. If a VxD stores PWR_OK through Return, it might overwrite a PWR_FAIL value that was written there by the previous device.

Only the virtual power device (VPOWERD) is permitted to send this message to devices. The EBX register must be zero on entry. The EDX register is reserved.

Note  This message is sent for compatibility with Windows 3.1 virtual devices. New virtual devices should use the VPOWERD_Register_Power_Handler service to be notified of changes in power state.