Control Register 4 (CR4) Extensions
3-7
18524C/0—Nov1996
AMD-K5 Processor Technical Reference Manual
Figure 3-1 and Table 3-1 show the fields in CR4. Figure 3-4 and
Table 3-2 show the fields in a page-directory entry.
4-Kbyte page translation differs from 4-Mbyte page translation
in the following ways:
■
4-Kbyte Paging (Figure 3-2)—Bits 31–22 of the linear address
select an entry in a 4-Kbyte page directory in memory,
whose physical base address is stored in CR3. Bits 21–12 of
the linear address select an entry in a 4-Kbyte page table in
memory, whose physical base address is specified by bits
31–22 of the page-directory entry. Bits 11–0 of the linear
address select a byte in a 4-Kbyte page, whose physical base
address is specified by the page-table entry.
■
4-Mbyte Paging (Figure 3-3)—Bits 31–22 of the linear
address select an entry in a 4-Mbyte page directory in mem-
ory, whose physical base address is stored in CR3. Bits 21–0
of the linear address select a byte in a 4-Mbyte page in
memory, whose physical base address is specified by bits
31–22 of the page-directory entry. Bits 21–12 of the page-
directory entry must be cleared to 0.
Figure 3-4. Page-Directory Entry (PDE)
Available to Software
AVL
11–9
Global
G
8
Page Size
PS
7
Dirty = 0
D
6
Accessed
A
5
Page Cache Disable
PCD
4
Page Writethrough
PWT
3
User/Supervisor
U/S
2
Write/Read
W/R
1
Present (valid)
P
0
8
7
6
5
4
3
2
1
0
31
P
C
D
U
/
S
W
/
R
G
9
10
11
12
A
V
L
P
S
A
P
W
T
P
Physical Base Address
0
Summary of Contents for AMD-K5
Page 1: ...AMD K5 Processor Technical Reference Manual TM...
Page 10: ...x AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 24: ...1 4 Overview AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 54: ...2 30 Internal Architecture AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 116: ...4 26 Performance AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 356: ...6 44 System Design AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 380: ...7 24 Test and Debug AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 396: ...A 16 AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 406: ...I 10 Index AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...