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INT 67 - Virtual Control Program Interface - SWITCH TO PROTECTED MODE
        AX = DE0Ch
        ESI = linear address in first megabyte of values for system registers
        interrupts disabled
Return: interrupts disabled
        GDTR, IDTR, LDTR, TR loaded
        SS:ESP must have at least 16 bytes space, and the entry point is
                required to set up a new stack before enabling interrupts
        EAX, ESI, DS, ES, FS, GS destroyed
SeeAlso: INT 15/AH=89h

Note:   in protected mode, calling the protected-mode VCPI entry point with
          AX = DE0Ch
          DS = segment selector from function DE01h
          SS:ESP in first megabyte of linear memory
          STACK:QWORD  return address from FAR call to 32-bit segment
                DWORD  EIP
                DWORD  CS
                DWORD  reserved for EFLAGS
                DWORD  ESP
                DWORD  SS
                DWORD  ES
                DWORD  DS
                DWORD  FS
                DWORD  GS
          and interrupts disabled, will switch to virtual86 mode with
          interrupts disabled, all segment registers loaded, and EAX destroyed.

Format of system register values for switch to protected mode:
Offset  Size    Description
 00h    DWORD   value for CR3
 04h    DWORD   linear address in first megabyte of value for GDTR
 08h    DWORD   linear address in first megabyte of value for IDTR
 0Ch    WORD    value for LDTR
 0Eh    WORD    value for TR
 10h    PWORD   CS:EIP of protected mode entry-point