5.4 Extension Window Base 0, 1 Registers
Thebridgesupportstwoextensionwindowsthatdefineanaddressrangedecodedasdescribedinthewindowenable
registerandwindowmapregister. Theextensionwindowbaseregistersdefinethe32-bitbaseaddressofthewindow.
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Name
Type
Default
Bit
Extension window base 0, 1
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Name
Type
Default
Extension window base 0, 1
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R
0
R
0
Register:
Type:
Offset:
Default:
Extension window base 0, 1
Read-only, Read/Write
44h, 4Ch
0000 0000h
5.5 Extension Window Limit 0, 1 Registers
The bridge supports two extension windows. Each window defines an address range that is decoded as described
in the window enable register and window map register. The extension window limit registers define the 32-bit limit
address of the window.
Bits 0 and 1 of this register determine whether the extension window is a prefetchable memory window, a
nonprefetchable window, or an I/O window. These bits are encoded as:
00 = Nonprefetchable memory
01 = Prefetchable memory
1x = I/O
Memory windows have a 4–Kbyte granularity and I/O windows have a doubleword (4-byte) granularity. When a
memory window is selected, bits 11–2 have no effect and are assumed to be 1s for the limit register and 0s for the
base register. This is consistent with the 4K-byte granularity of the memory windows.
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Name
Type
Default
Bit
Extension window limit 0, 1
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Name
Type
Default
Extension window limit 0, 1
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Register:
Type:
Extension window limit 0, 1
Read/Write
Offset:
Default:
48h, 50h
0000 0000h
5–4
TI [ TEXAS INSTRUMENTS ]
