Int 2F Fn ED03  R - Phar Lap 386/dos-extender V4.1 - Get Extender Entry P  [E]

   AX = ED03h
   CX = real-mode code segment
   DX = real-mode data segment

Return: CF clear if successful
       CX = protected-mode code segment selector
       DX = protected-mode data segment selector
       ES:DI -> real-mode entry point for calling protected-mode functions
             (see INT 21/AX=250Dh)
   CF set on error
       AX = error code
       0008h unable to allocate LDT descriptors