Intel 253668-032US Manual Do Utilizador
4-22 Vol. 3
PAGING
Table 4-11. Format of a PAE Page-Table Entry that Maps a 4-KByte Page
Bit
Position(s)
Contents
0 (P)
Present; must be 1 to map a 4-KByte page
1 (R/W)
Read/write; if 0, writes may not be allowed to the 4-KByte page referenced by this
entry (depends on CPL and CR0.WP; see Section 4.6)
2 (U/S)
User/supervisor; if 0, accesses with CPL=3 are not allowed to the 4-KByte page
referenced by this entry (see Section 4.6)
3 (PWT)
Page-level write-through; indirectly determines the memory type used to access
the 4-KByte page referenced by this entry (see Section 4.9)
4 (PCD)
Page-level cache disable; indirectly determines the memory type used to access
the 4-KByte page referenced by this entry (see Section 4.9)
5 (A)
Accessed; indicates whether software has accessed the 4-KByte page referenced
by this entry (see Section 4.8)
6 (D)
Dirty; indicates whether software has written to the 4-KByte page referenced by
this entry (see Section 4.8)
7 (PAT)
If the PAT is supported, indirectly determines the memory type used to access the
4-KByte page referenced by this entry (see Section 4.9); otherwise, reserved
(must be 0)
1
8 (G)
Global; if CR4.PGE = 1, determines whether the translation is global (see Section
4.10); ignored otherwise
11:9
Ignored
M–1:12
Physical address of the 4-KByte page referenced by this entry
62:M
Reserved (must be 0)
63 (XD)
If IA32_EFER.NXE = 1, execute-disable (if 1, instruction fetches are not allowed
from the 4-KByte page controlled by this entry; see Section 4.6); otherwise,
reserved (must be 0)
NOTES:
1. See Section 4.1.4 for how to determine whether the PAT is supported.