Intel IA-32 Manuale Utente
Vol. 3A 3-23
PROTECTED-MODE MEMORY MANAGEMENT
3.7.1
Linear Address Translation (4-KByte Pages)
Figure 3-12 shows the page directory and page-table hierarchy when mapping linear addresses
to 4-KByte pages. The entries in the page directory point to page tables, and the entries in a page
table point to pages in physical memory. This paging method can be used to address up to 2
to 4-KByte pages. The entries in the page directory point to page tables, and the entries in a page
table point to pages in physical memory. This paging method can be used to address up to 2
20
pages, which spans a linear address space of 2
32
bytes (4 GBytes).
Table 3-3. Page Sizes and Physical Address Sizes
PG Flag,
CR0
PAE Flag,
CR4
PSE Flag,
CR4
PS Flag,
PDE
PSE-36 CPUID
Feature Flag
Page Size
Physical Address
Size
0
X
X
X
X
—
Paging Disabled
1
0
0
X
X
4 KBytes
32 Bits
1
0
1
0
X
4 KBytes
32 Bits
1
0
1
1
0
4 MBytes
32 Bits
1
0
1
1
1
4 MBytes
36 Bits
1
1
X
0
X
4 KBytes
36 Bits
1
1
X
1
X
2 MBytes
36 Bits
Figure 3-12. Linear Address Translation (4-KByte Pages)
0
Directory
Table
Offset
Page Directory
Directory Entry
CR3 (PDBR)
Page Table
Page-Table Entry
4-KByte Page
Physical Address
31
21
11
12
22
Linear Address
1024 PDE
∗ 1024 PTE = 2
20
Pages
32*
10
12
10
*32 bits aligned onto a 4-KByte boundary.
20