Limitations of Dynamically Loadable VxDs

Limitations of Dynamically Loadable VxDs

Some limitations are imposed on dynamically loadable VxDs.

If a dynamically loadable VxD provides VXD services, it cannot be dynamically unloaded.
Dynamically loadable VxDs must release any acquired resources when they are unloaded; the system does not release the resources automatically.
Certain non-releasable resources (for example, V86/PM break points) should not be reallocated every time a dynamically loadable VxD is loaded. Because the static data and code segments are never unloaded, they should be used to store the resources and then reused when the VxD is loaded again.
The following services are provided only during initialization and are not available to dynamically loadable VxDs.

_Add_Global_V86_Data_Area	Get_Next_Arena
_AddFreePhysPage	Get_Next_Profile_String
_AddInstanceItem	Get_Profile_Boolean
_Allocate_Global_V86_Data_Area	Get_Profile_Decimal_Int
_Allocate_Temp_V86_Data_Area	Get_Profile_Fixed_Point
_Free_Temp_V86_Data_Area	Get_Profile_Hex_Int
Get_Profile_String	GetDOSVectors
_SetLastV86Page	Locate_Byte_In_ROM
Allocate_PM_App_CB_Area	MMGR_SetNULPageAddr
Convert_Boolean_String	OpenFile
Convert_Decimal_String	PageSwap_Init_File
Convert_Fixed_Point_String	Set_Physical_HMA_Alias
Convert_Hex_String	V86MMGR_NoUMBInitCalls
DOSMGR_BackFill_Allowed	V86MMGR_Set_Mapping_Info
DOSMGR_Enable_Indos_Polling	V86MMGR_SetAvailMapPgs
DOSMGR_Instance_Device	V86MMGR_SetLocalA20
Get_Name_Of_Ugly_TSR	VDMAD_Reserve_Buffer_Space