AMD AMD5K86 - Page 61

AMD~
AMD5,JJ6 Processor Technical Reference Manual
18524BjO-Mar1996
4-Mbyte
Page
Directory
r-+
PDE
l
CR3
I
--
31 22 21
Page Directory
Offset
r--
4-Mbyte
Page
1 1
-
Byte
Page
Offset
Linear Address
0
FIGURE 3-3. 4-Mbyte Paging Mechanism
3-6
To enable the 4-Mbyte paging option:
1. Set the Page Size Extension (PSE) bit in CR4 to 1.
2. Set the Page Size (PS) bit in the page-directory entry to 1.
3. Write the physical base addresses of 4-Mbyte pages in bits
31-22 of page-directory entries. (Bits 21-12 of these entries
must be cleared to 0 or the processor will generate a page
fault.)
4. Load CR3 with the base address of the page directory that,.
contains these page-directory entries.
Software Environment and Extensions