Mips Technologies R4000 - Page 107

MIPS R4000 Microprocessor User's Manual 77
Memory Management
Table 4-4 64-bit Kernel Mode Segments
64-bit Kernel Mode, User Space (xkuseg)
In Kernel mode, when KX = 1 in the Status register and bits 63:62 of the 64-
bit virtual address are 00
2
, the xkuseg virtual address space is selected; it
covers the current user address space. The virtual address is extended
with the contents of the 8-bit ASID field to form a unique virtual address.
When ERL = 1 in the Status register, the user address region becomes a 2
31
-
byte unmapped (that is, mapped directly to physical addresses) uncached
address space. See the Cache Error exception in Chapter 5 for more
information.
Address Bit
Values
Status Register
Is One Of These
Values
Segment
Name
Address Range
Segment
Size
KSU EXL ERL KX
A(63:62) = 00
2
KSU = 00
2
or
EXL = 1
or
ERL =1
1 xksuseg
0x0000 0000 0000 0000
through
0x0000 00FF FFFF FFFF
1 Tbyte
(2
40
bytes)
A(63:62) = 01
2
1 xksseg
0x4000 0000 0000 0000
through
0x4000 00FF FFFF FFFF
1 Tbyte
(2
40
bytes)
A(63:62) = 10
2
1 xkphys
0x8000 0000 0000 0000
through
0xBFFF FFFF FFFF FFFF
8 2
36
-byte
spaces
A(63:62) = 11
2
1 xkseg
0xC000 0000 0000 0000
through
0xC000 00FF 7FFF FFFF
(2
40
–2
31
)
bytes
A(63:62) = 11
2
A(61:31) = -1
1 ckseg0
0xFFFF FFFF 8000 0000
through
0xFFFF FFFF 9FFF FFFF
512 Mbytes
(2
29
bytes)
A(63:62) = 11
2
A(61:31) = -1
1 ckseg1
0xFFFF FFFF A000 0000
through
0xFFFF FFFF BFFF FFFF
512 Mbytes
(2
29
bytes)
A(63:62) = 11
2
A(61:31) = -1
1 cksseg
0xFFFF FFFF C000 0000
through
0xFFFF FFFF DFFF FFFF
512 Mbytes
(2
29
bytes)
A(63:62) = 11
2
A(61:31) = -1
1 ckseg3
0xFFFF FFFF E000 0000
through
0xFFFF FFFF FFFF FFFF
512 Mbytes
(2
29
bytes)