NEC Network Controller uPD98502 - Manual (Page 113)

CHAPTER 2 V R 4120A
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, the
kseg3 virtual address space is selected; it is the current 512-Mbyte (2
29
-byte) kernel virtual space. The virtual
address 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
(2
40
bytes)
A(63:62) = 01 1 xksseg 4000_0000_0000_0000H
to
4000_00FF_FFFF_FFFFH
TLB map 1 Tbyte
(2
40
bytes)
A(63:62) = 10 1 xkphys 8000_0000_0000_0000H
to
BFFF_FFFF_FFFF_FFFFH
0000_0000H
to
FFFF_FFFFH
4 Gbytes
(2
32
bytes)
A(63:62) = 11 1 xkseg C000_0000_0000_0000H
to
C000_00FF_7FFF_FFFFH
TLB map 2
40
to 2
31
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
(2
29
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
(2
29
bytes)
A(63:62) = 11
A(63:31) = -1
1 cksseg FFFF_FFFF_C000_0000H
to
FFFF_FFFF_DFFF_FFFFH
TLB map 512 Mbytes
(2
29
bytes)
A(63:62) = 11
A(63:31) = -1
1 ckseg3 FFFF_FFFF_E000_0000H
to
FFFF_FFFF_FFFF_FFFFH
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
40
bytes) current user address space. The virtual address is
extended 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 (2
31
bytes) without TLB
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.