Request control functions are used by the FSD to manage requests after they have been submitted to obtain advisory information from the physical device driver and to pass advisory information to the physical device driver. Entry points are exported by the physical device driver through the GET DRIVER CAPABILITIES command. Request control functions can be called at interrupt time and cannot block. Request control functions need only preserve segment registers.

The following request control functions are defined:

• DD_SetFSDInfo
  
• DD_ChgPriority
  
• DD_SetRestPos
  
• DD_GetBoundary