4.23 Prefetchable Memory Limit Register
The prefetchable memory limit register defines the upper-limit address of a prefetchable memory address range used
to determine when to forward memory transactions from one interface to the other. The upper 12 bits of this register
are read/write and correspond to the address bits AD31–AD20. The lower 20 address bits are considered 1s; thus,
the address range is aligned to a 1M-byte boundary. The bottom four bits are read-only and return 0s when read.
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Name
Type
Default
Prefetchable memory limit
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
R
0
R
0
Register:
Type:
Prefetchable memory limit
Read-only, read/write
Offset:
Default:
26h
0000h
4.24 Prefetchable Base Upper 32 Bits Register
The PCI2250 does not support 64-bit addressing; thus, the prefetchable base upper 32-bit register is read-only and
returns 0s when read.
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Name
Type
Default
Bit
Prefetchable base upper 32 bits
R
0
R
0
R
0
R
0
R
0
R
0
R
0
9
R
0
8
R
0
7
R
0
6
R
0
5
R
0
4
R
0
3
R
0
2
R
0
1
R
0
0
15
14
13
12
11
10
Name
Type
Default
Prefetchable base upper 32 bits
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
Register:
Type:
Offset:
Default:
Prefetchable base upper 32 bits
Read-only
28h
0000 0000h
4.25 Prefetchable Limit Upper 32 Bits Register
The PCI2250 does not support 64-bit addressing; thus the prefetchable limit upper 32-bit register is read-only and
returns 0s when read.
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Name
Type
Default
Bit
Prefetchable limit upper 32 bits
R
0
R
0
R
0
R
0
R
0
R
0
R
0
9
R
0
8
R
0
7
R
0
6
R
0
5
R
0
4
R
0
3
R
0
2
R
0
1
R
0
0
15
14
13
12
11
10
Name
Type
Default
Prefetchable limit upper 32 bits
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
Register:
Type:
Offset:
Default:
Prefetchable limit upper 32 bits
Read-only
2Ch
0000 0000h
4–12
TI [ TEXAS INSTRUMENTS ]
