==== FSH_CALLDRIVER ====

**Purpose**

This routine allows FSDs to call a device driver's Extended Strategy entry point.   

**Calling Sequence**

<code c>
int far pascal FSH_CALLDRIVER(pPkt, hVPB, fControl)

void far * pPkt;
unsigned short hVPB;
unsigned short fControl;
</code>

**Where**

//pPkt// is a pointer to device driver Extended strategy request packet.   

//hVPB// is the volume handle for the source of I/O.   

//fControl// is the bit mask of pop-up control actions: 

|Bit 0 off |indicates volume change pop-up desired |
|Bit 0 on |indicates no volume change pop-up |
|All other bits are reserved and must be zero. ||

**Returns**

If no error is detected, a zero error code is returned. If an error is detected, one of the following error codes is returned:   

  * ERROR_VOLUME_CHANGED -- is an indication that removable media volume change has occurred.
  * ERROR_INVALID_PARAMETER -- the fControl flag word has reserved bits on. 

**Remarks**

This routine should be called for any Extended strategy requests going to a drive that has removable media.   

For a detailed description of the Extended Strategy request interface please see the OS/2 Version 2.0 Physical Device Driver Reference   

//FSH_CALLDRIVER// may block.   

Note:   OS/2 does not validate input parameters. Therefore, an FSD should call //FSH_PROBEBUF// where appropriate.