Intel IA-32 Manuale Utente
Vol. 3A 3-41
PROTECTED-MODE MEMORY MANAGEMENT
•
Page-directory entry — Bits 29:21 provide an offset to an entry in the page directory. The
selected entry provides the base physical address of a 2-MByte page.
selected entry provides the base physical address of a 2-MByte page.
•
Page offset — Bits 20:0 provides an offset to a physical address in the page.
3.10.3
Enhanced Paging Data Structures
Figure 3-26 shows the format for the PML4 table, page-directory-pointer table, page-direc-
tory and page-table entries when 4-KByte pages are used in IA-32e mode. Figure 3-27
shows the format for the PML4 table, the page-directory-pointer table and page-directory
entries when 2-MByte pages are used in IA-32e mode.
tory and page-table entries when 4-KByte pages are used in IA-32e mode. Figure 3-27
shows the format for the PML4 table, the page-directory-pointer table and page-directory
entries when 2-MByte pages are used in IA-32e mode.
Except for the PML4 table, these enhanced formats of page-directory-pointer table, page-
directory, and page-table entries are also used in enhanced legacy PAE-enabled paging on
processors that supports Intel EM64T (see Section 3.8.1, “Enhanced Legacy PAE Paging”).
directory, and page-table entries are also used in enhanced legacy PAE-enabled paging on
processors that supports Intel EM64T (see Section 3.8.1, “Enhanced Legacy PAE Paging”).
Figure 3-25. IA-32e Mode Paging Structures (2-MByte pages)
Directory Ptr
Linear Address
Dir. Pointer Entry
CR3 (PML4)
39 38
Pointer Table
512 PML4 *512 PDPTE
∗ 512 PDE = 2
27
Pages
9
9
40
1
21
1. 40 bits aligned onto a 4-KByte boundary
19
2-MByte Page
Offset
Physical Addr
Directory Entry
0
20
21
Directory
30 29
Page-Directory-
Page-Directory
PML4
47
48
63
Sign Extended
9
PML4 Entry
NOTE: