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CHAPTER 4 MEMORY MANAGEMENT SYSTEM
66
(c) kseg1 (32-bit Kernel mode, kernel space 1)
When KX = 0 in the Status register and the most-significant three bits of the virtual address space are
101, the kseg1 virtual address space is selected; it is the current 512-Mbyte (2
References to kseg1 are not mapped through the TLB; the physical address selected is defined by
subtracting 0xA000 0000 from the virtual address.
Caches are disabled for accesses to these addresses, and main memory (or memory-mapped I/O
device registers) are accessed directly.
29
-byte) physical space.
(d) ksseg (32-bit Kernel mode, supervisor space)
When KX = 0 in the Status register and the most-significant three bits of the virtual address space are
110, the ksseg virtual address space is selected; it is the current 512-Mbyte (2
space. The virtual address is extended with the contents of the 8-bit ASID field to form a unique virtual
address.
29
-byte) virtual address
(e) kseg3 (32-bit Kernel mode, kernel space 3)
When KX = 0 in the Status register and the most-significant three bits of the virtual address space are
111, the kseg3 virtual address space is selected; it is the current 512-Mbyte (2
space. The virtual address is extended with the contents of the 8-bit ASID field to form a unique virtual
address.
29
-byte) kernel virtual
Table 4-4. 64-bit Kernel Mode Segments
Address bit
value
Status register bit
value
Segmen
t name
Virtual address
Physical
address
Size
KSU EXL ERL
KX
64-bit
A[63..62] = 00
KSU = 00
or
EXL = 1
or
ERL = 1
1
xksuseg
0x0000 0000 0000 0000
to
0x0000 00FF FFFF FFFF
TLB map
1 Tbyte
(2
40
bytes)
64-bit
A[63..62] = 01
1
xksseg
0x4000 0000 0000 0000
to
0x4000 00FF FFFF FFFF
TLB map
1 Tbyte
(2
40
bytes)
64-bit
A[63..62] = 10
1
xkphys
0x8000 0000 0000 0000
to
0xBFFF FFFF FFFF FFFF
0x0000 0000
to
0xFFFF FFFF
4 Gbytes
(2
32
bytes)
64-bit
A[63..62] = 11
1
xkseg
0xC000 0000 0000 0000
to
0xC000 00FF 7FFF FFFF
TLB map
2
40
- 2
bytes
31