typedef struct _KTRAP_FRAME {


//
//  Following 4 values are only used and defined for DBG systems,
//  but are always allocated to make switching from DBG to non-DBG
//  and back quicker.  They are not DEVL because they have a non-0
//  performance impact.
//

    ULONG   DbgEbp;         // Copy of User EBP set up so KB will work.
    ULONG   DbgEip;         // EIP of caller to system call, again, for KB.
    ULONG   DbgArgMark;     // Marker to show no args here.
    ULONG   DbgArgPointer;  // Pointer to the actual args

//
//  Temporary values used when frames are edited.
//
//
//  NOTE:   Any code that want's ESP must materialize it, since it
//          is not stored in the frame for kernel mode callers.
//
//          And code that sets ESP in a KERNEL mode frame, must put
//          the new value in TempEsp, make sure that TempSegCs holds
//          the real SegCs value, and put a special marker value into SegCs.
//

    ULONG   TempSegCs;
    ULONG   TempEsp;

//
//  Debug registers.
//

    ULONG   Dr0;
    ULONG   Dr1;
    ULONG   Dr2;
    ULONG   Dr3;
    ULONG   Dr6;
    ULONG   Dr7;

//
//  Segment registers
//

    ULONG   SegGs;
    ULONG   SegEs;
    ULONG   SegDs;

//
//  Volatile registers
//

    ULONG   Edx;
    ULONG   Ecx;
    ULONG   Eax;

//
//  Nesting state, not part of context record
//

    ULONG   PreviousPreviousMode;

    PEXCEPTION_REGISTRATION_RECORD ExceptionList;
                                            // Trash if caller was user mode.
                                            // Saved exception list if caller
                                            // was kernel mode or we're in
                                            // an interrupt.

//
//  FS is TIB/PCR pointer, is here to make save sequence easy
//

    ULONG   SegFs;

//
//  Non-volatile registers
//

    ULONG   Edi;
    ULONG   Esi;
    ULONG   Ebx;
    ULONG   Ebp;

//
//  Control registers
//

    ULONG   ErrCode;
    ULONG   Eip;
    ULONG   SegCs;
    ULONG   EFlags;

    ULONG   HardwareEsp;    // WARNING - segSS:esp are only here for stacks
    ULONG   HardwareSegSs;  // that involve a ring transition.

    ULONG   V86Es;          // these will be present for all transitions from
    ULONG   V86Ds;          // V86 mode
    ULONG   V86Fs;
    ULONG   V86Gs;
} KTRAP_FRAME;