CHAPTER 5 MEMORY MANAGEMENT SYSTEM
132
Table 5-4. 64-bit Kernel Mode Segments
Address bit
Status register bit value
Segment
Virtual address
Physical
Size
value
KSU
EXL
ERL
KX
name
address
64-bit
A[63..62] = 00
1
xkuseg
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
64-bit
A[63..62] = 11
A[63..31] = -1
1
ckseg0
0xFFFF FFFF 8000 0000
to
0xFFFF FFFF 9FFF FFFF
0x0000 0000
to
0x1FFF FFFF
512 Mbytes
(2
29
bytes)
64-bit
A[63..62] = 11
A[63..31] = -1
1
ckseg1
0xFFFF FFFF A000 0000
to
0xFFFF FFFF BFFF FFFF
0x0000 0000
to
0x1FFF FFFF
512 Mbytes
(2
29
bytes)
64-bit
A[63..62] = 11
A[63..31] = -1
1
cksseg
0xFFFF FFFF C000 0000
to
0xFFFF FFFF DFFF FFFF
TLB map
512 Mbytes
(2
29
bytes)
64-bit
A[63..62] = 11
A[63..31] = -1
KSU = 00
or
EXL = 1
or
ERL = 1
1
ckseg3
0xFFFF FFFF E000 0000
to
0xFFFF FFFF FFFF FFFF
TLB map
512 Mbytes
(2
29
bytes)
(6) xkuseg (64-bit Kernel mode, user space)
When KX = 1 in the Status register and bits 63 and 62 of the virtual address space are 00, the xkuseg virtual
address space is selected; it is the 1-Tbyte (2
extended with the contents of the 8-bit ASID field to form a unique virtual address.
References to xkuseg are mapped through TLB. Whether cache can be used or not is determined by bit C of
each page’s TLB entry.
If the ERL bit of the Status register is 1, the user address space is assigned 2 Gbytes (2
mapping and becomes unmapped (with virtual addresses being used as physical addresses) and uncached so
that the cache error handler can use it. This allows the Cache Error exception code to operate uncached using
r0 as a base register.
40
bytes) current user address space. The virtual address is
31
bytes) without TLB
(7) xksseg (64-bit Kernel mode, current supervisor space)
When KX = 1 in the Status register and bits 63 and 62 of the virtual address space are 01, the xksseg address
space is selected; it is the 1-Tbyte (2
with the contents of the 8-bit ASID field to form a unique virtual address.
References to xksseg are mapped through TLB. Whether cache can be used or not is determined by bit C of
each page’s TLB entry.
40
bytes)current supervisor address space. The virtual address is extended