Int 21 Fn 250D  P - Phar Lap 386/dos-extender - Get Real-mode Link Inform  [E]

   AX = 250Dh

Return: CF clear
   EAX = CS:IP of real-mode callback procedure that will call through
       from real mode to a protected-mode routine
   EBX = 32-bit real-mode address of intermode call data buffer
   ECX = size in bytes of intermode call data buffer
   ES:EDX = protected-mode address of intermode call data buffer

Notes: this function is also supported by FlashTek X-32VM
   X-32VM guarantees the intermode buffer to be at least 4 KB

See Also: AX=250Eh

Call real-mode callback with:
   STACK:  DWORD   offset to protected-mode code
       WORD    placeholder for protected-mode CS
       DWORD   pointer to selector structure (see below)
           or 0000h:0000h for defaults
       var parameters for protected-mode procedure

Return: via FAR return

Format of selector structure:
Offset Size    Description
 00h   WORD    protected-mode GS selector
 02h   WORD    protected-mode FS selector
 04h   WORD    protected-mode ES selector
 06h   WORD    protected-mode DS selector