Mips Technologies R4000 - Bad Virtual Address Register (Badvaddr) (8); Count Register (9)

MIPS R4000 Microprocessor User's Manual 103
CPU Exception Processing
Bad Virtual Address Register (BadVAddr) (8)
The Bad Virtual Address register (BadVAddr) is a read-only register that
displays the most recent virtual address that caused one of the following
exceptions: TLB Invalid, TLB Modified, TLB Refill, Virtual Coherency
Data Access, or Virtual Coherency Instruction Fetch.
Figure 5-2 shows the format of the BadVAddr register.
Figure 5-2 BadVAddr Register Format
Note: The BadVAddr register does not save any information for bus errors,
since bus errors are not addressing errors.
Count Register (9)
The Count register acts as a timer, incrementing at a constant rate—half the
maximum instruction issue rate—whether or not an instruction is
executed, retired, or any forward progress is made through the pipeline.
This register can be read or written. It can be written for diagnostic
purposes or system initialization; for example, to synchronize processors.
Figure 5-3 shows the format of the Count register.
Figure 5-3 Count Register Format
BadVAddr Register
31 0
32
Bad Virtual Address
63 0
64
Bad Virtual Address
32-bit
Mode
64-bit
Mode
Count Register
31 0
32
Count