CHAPTER 7 INITIALIZATION INTERFACE
211
(4) Hibernate Mode
When the HIBERNATE instruction has been executed, the processor can be set to Hibernate mode. During
Hibernate mode, the processor stops supplying clocks to all units. The register and cache contents are retained
and output of TClock and MasterOut is stopped. The processor remains in Hibernate mode until the POWER
pin is asserted, a WakeUpTimer interrupt occurs, DCD# pin is asserted, or GPIO[3] is asserted, at which the
processor returns to Fullspeed mode.
Power consumption during Hibernate mode is about 0 W (it does not go completely to 0 W due to the existence
of a 32.768-kHz oscillator, on-chip peripheral units that operate at 32.768 kHz, or DRAM self refresh).
7.4.2 Privilege Mode
The V
R
4102 supports three system modes: kernel expanded addressing mode, supervisor expanded addressing
mode, and user expanded addressing mode. These three modes are described below.
(1) Kernel Expanded Addressing Mode
When the Status register’s KX bit has been set, an expanded TLB miss exception vector is used when a TLB
miss occurs for the kernel address. While in kernel mode, the MIPS III operation code can always be used,
regardless of the KX bit.
(2) Supervisor Expanded Addressing Mode
When the Status register’s SX bit has been set, the MIPS III operation code can be used when in supervisor
mode and an expanded TLB miss exception vector is used when a TLB miss occurs for the supervisor address.
(3) User Expanded Addressing Mode
When the Status register’s UX bit has been set, the MIPS III operation code can be used when in user mode,
and an expanded TLB miss exception vector is used when a TLB miss occurs for the user address. When this
bit is cleared, the MIPS I and II operation codes can be used, as can 32-bit virtual addresses.
7.4.3 Reverse Endian
When the Status register’s RE bit has been set, the endian ordering is reversed to adopt the user software’s
perspective. However, the RE bit of the Status register must be set to 0 since the V
R
4102 supports the little-endian
order only.
7.4.4 Bootstrap Exception Vector (BEV)
The BEV bit is used to generate an exception during operation testing (diagnostic testing) of the cache and main
memory system. This bit is automatically set to 1 after reset or NMI exception.
When the Status register’s BEV bit has been set, the address of the TLB miss exception vector is changed to the
virtual address 0xFFFF FFFF BFC0 0200 and the ordinary execution vector is changed to address 0xFFFF FFFF
BFC0 0380.
When the BEV bit is cleared, the TLB miss exception vector’s address is changed to 0xFFFF FFFF 8000 0000
and the ordinary execution vector is changed to address 0xFFFF FFFF 8000 0180.