
CHAPTER 4 MEMORY MANAGEMENT SYSTEM
62
Table 4-2. 32-bit and 64-bit Supervisor Mode Segments
Address bit
value
Status register bit value
Segmen
t name
Address range
Size
KS
U
EXL
ER
L
SX
32-bit
A[31] = 0
01
0
0
0
suseg
0x0000 0000
to
0x7FFF FFFF
2 Gbytes
(2
31
bytes)
32-bit
A[31..29] =
110
01
0
0
0
sseg
0xC000 0000
to
0xDFFF FFFF
512
Mbytes
(2
29
bytes)
64-bit
A[63..62] = 00
01
0
0
1
xsuseg
0x0000 0000 0000
0000
to
0x0000 00FF FFFF
FFFF
1 Tbyte
(2
40
bytes)
64-bit
A[63..62] = 01
01
0
0
1
xsseg
0x4000 0000 0000
0000
to
0x4000 00FF FFFF
FFFF
1 Tbyte
(2
40
bytes)
64-bit
A[63..62] = 11
01
0
0
1
csseg
0xFFFF FFFF C000
0000
to
0xFFFF FFFF DFFF
FFFF
512
Mbytes
(2
29
bytes)
(a) suseg (32-bit Supervisor mode, user space)
When SX = 0 in the Status register and the most-significant bit of the virtual address space is set to 0,
the suseg virtual address space is selected; it covers 2 Gbytes (2
space. The virtual address is extended with the contents of the 8-bit ASID field to form a unique virtual
address. This mapped space starts at virtual address 0x0000 0000 and runs through 0x7FFF FFFF.
31
bytes) of the current user address
(b) sseg (32-bit Supervisor mode, supervisor space)
When SX = 0 in the Status register and the three most-significant bits of the virtual address space are
110, the sseg virtual address space is selected; it covers 512 Mbytes (2
supervisor virtual address space. The virtual address is extended with the contents of the 8-bit ASID
field to form a unique virtual address. This mapped space begins at virtual address 0xC000 0000 and
runs through 0xDFFF FFFF.
29
bytes) of the current