## MMPM/2 Device Driver Reference

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### VSD_OPEN - Syntax

This command opens the device driver and returns a VSD handle or (HVSD). It should not allocate resources on the device (resource usage should be performed on the VSD restore).

VSD_OPEN is a required command and must be implemented by all VSD writers.

This command is sent using VSDEntry as follows:

        VSDEntry(hvsd, ulFunc, ulFlags, pRequest)

hvsd (HVSD) Not used.

ulFunc (ULONG) Set to VSD_OPEN.

ulFlags (ULONG) No flags used for this command.

pRequest (PVSD_OPEN_PARMS) Pointer to the VSD_OPEN_PARMS data structure.

rc (ULONG) Error code indicating success or the type of failure:

VSDERR_SUCCESS Command completed successfully.

VSDERR_MISSING_PARAMETER One or more parameters are missing.

VSDERR_NO_DEVICE_DRIVER VSD is not connected to a device driver.

VSDERR_DEVICE_REJECTED Device driver rejected the request.

VSDERR_HARDWARE A hardware error occurred.

VSDERR_INVALID_BUFF pRequest is not valid.