See Section 17.3.2 for more details about why this functionality is required.
DPMI_Int
Simulate a real-mode interrupt with the ability to set ALL registers, including segments, without causing a General Protection Fault. Essentially just a wrapper around DPMI function 0300h.
DPMI_Regs filled with real-mode interrupt register inputs.
BX = interrupt number to simulate.
DPMI_Regs filled with real-mode interrupt register outputs.
CF=1, AX=error code (see DPMI function 0300h for a list) if an error occurred, otherwise CF=0.
Clobbers CX, DX.
Important: Doesn't use C calling convention.