CHAPTER 2 VR4120A
Preliminary User’s Manual S15543EJ1V0UM 113
(5) 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, thekseg3 virtual address space is selected; it is the current 512-Mbyte (229-byte) kernel virtual space. The virtualaddress is extended with the contents of the 8-bit ASID field to form a unique virtual address.Table 2-30. 64-bit Kernel Mode Segments
Address Bit Status Register Bit Value Segment Virtual Address Physical Size
Value KSU EXL ERL KX Name Address
A(63:62) = 00 KSU = 00
or
EXL = 1
or
ERL = 1
1 xkuseg 0000_0000_0000_0000H
to
0000_00FF_FFFF_FFFFH
TLB map 1 Tbyte
(240 bytes)
A(63:62) = 01 1 xksseg 4000_0000_0000_0000H
to
4000_00FF_FFFF_FFFFH
TLB map 1 Tbyte
(240 bytes)
A(63:62) = 10 1 xkphys 8000_0000_0000_0000H
to
BFFF_FFFF_FFFF_FFFFH
0000_0000H
to
FFFF_FFFFH
4 Gbytes
(232 bytes)
A(63:62) = 11 1 xkseg C000_0000_0000_0000H
to
C000_00FF_7FFF_FFFFH
TLB map 240 to 231
bytes
A(63:62) = 11
A(63:31) = -1
1 ckseg0 FFFF_FFFF_8000_0000H
to
FFFF_FFFF_9FFF_FFFFH
0000_0000H
to
1FFF_FFFFH
512 Mbytes
(229 bytes)
A(63:62) = 11
A(63:31) = -1
1 ckseg1 FFFF_FFFF_A000_0000H
to
FFFF_FFFF_BFFF_FFFFH
0000_0000H
to
1FFF_FFFFH
512 Mbytes
(229 bytes)
A(63:62) = 11
A(63:31) = -1
1 cksseg FFFF_FFFF_C000_0000H
to
FFFF_FFFF_DFFF_FFFFH
TLB map 512 Mbytes
(229 bytes)
A(63:62) = 11
A(63:31) = -1
1 ckseg3 FFFF_FFFF_E000_0000H
to
FFFF_FFFF_FFFF_FFFFH
TLB map 512 Mbytes
(229 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 virtualaddress space is selected; it is the 1-Tbyte (240 bytes) current user address space. The virtual address isextended with the contents of the 8-bit ASID field to form a unique virtual address.If the ERL bit of the Status register is 1, the user address space is assigned 2 Gbytes (231 bytes) without TLBmapping and becomes unmapped (with virtual addresses being used as physical addresses) and uncached sothat the cache error handler can use it. This allows the Cache Error exception code to operate uncached using r0as a base register.