Int 31/AX=0300h

DPMI 0.9+ - SIMULATE REAL MODE INTERRUPT

AX = 0300h
BL = interrupt number
BH = flags
bit 0:
Reset the interrupt controller and A20 line (DPMI 0.9)
reserved, must be 0 (DPMI 1.0+)
others:
Reserved, must be 0.
CX = number of words to copy from protected mode to real mode stack.
ES:(E)DI = selector:offset of real mode call structure (see #03148)

Return:
CF clear if successful
real mode call structure modified (all fields except SS:SP, CS:IP
filled with return values from real mode interrupt)
CF set on error
AX = error code (DPMI 1.0+) (8012h,8013h,8014h,8021h)(see #03143)
protected mode stack unchanged

Notes: 16-bit programs use ES:DI as pointer, 32-bit programs use ES:EDI. CS:IP in the real mode call structure is ignored for this call, instead, the indicated interrupt vector is used for the address. The flags in the call structure are pushed on the real mode stack to form an interrupt stack frame, and the trace and interrupt flags are clear on entry to the handler. DPMI will provide a small (30 words) real mode stack if SS:SP is zero. The real mode handler must return with the stack in the same state as it was on being called

See Also: AX=0302h - AX=FF01h - INT 21/AX=2511h - INT 21/AH=E3h"OS/286"

See Also: INT 2C/AX=0026h - INT 2F/AX=FB42h/BX=000Dh

Format of DPMI real mode call structure: Offset Size Description (Table 03148) 00h DWORD EDI 04h DWORD ESI 08h DWORD EBP 0Ch DWORD reserved (00h) 10h DWORD EBX 14h DWORD EDX 18h DWORD ECX 1Ch DWORD EAX 20h WORD flags 22h WORD ES 24h WORD DS 26h WORD FS 28h WORD GS 2Ah WORD IP 2Ch WORD CS 2Eh WORD SP 30h WORD SS

Category: DOS Extenders - Int 31h - D

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