Begin_Nest_V86_Exec

include vmm.inc

VMMcall Begin_Nest_V86_Exec

Sets the current virtual machine to V86 mode and prepares the virtual machine for nested execution. This service is used in conjunction with the End_Nest_Exec service to create a nested execution block in which a virtual device may call the Exec_Int, Resume_Exec, and various simulation services. Virtual devices use these services to call software in the virtual machine. Uses Client_CS, Client_IP, and Flags

• Returns a break point in Client_CS and Client_IP that is used by nested execution services.

When in a nested execution block, a virtual device may call the Exec_Int and Resume_Exec services any number of times.

This service should only be used by virtual devices that convert protected-mode calls into V86 calls. For example, the virtual MS-DOS manager uses this service to map calls to MS-DOS functions (Interrupt 21h) issued by protected-mode programs into calls to MS-DOS functions in V86 mode.

This service should be used by virtual devices that need to be sure that they are calling V86-mode code. A typical usage is translating a protected-mode call into a V86-mode call. After the parameters are translated, Begin_Nest_V86_Exec is used to ensure that the subsequent simulation is into V86-mode.

This service saves the current execution mode of the virtual machine, and End_Nest_Exec restores the mode.

See also Begin_Nest_Exec, End_Nest_Exec, Exec_Int, Resume_Exec