Register Description
Bits
Type
Reset
Description
5
RO
0
Extended Tag Field Supported (ETFS): This field indicates the maximum
supported size of the Tag Field. Defined encodings are:
0 = 5-bit Tag field supported
1 = 8-bit Tag field supported
The Intel® 6700PXH 64-bit PCI Hub only supports a 5-bit tag.
4:3
2:0
RO
RO
0
1
Reserved.
Supported Maximum Payload Size (SMPS): The Intel® 6700PXH 64-bit
PCI Hub supports a max payload size of 256 byte packets.
3.5.1.37
Offset 4Ch: EXP_DEVCNTL—PCI Express* Device Control
Register (D0:F0, F2)
Offset:
Default Value: 0000h
4C – 4Dh
Attribute: RW, RO
Size: 16 bits
This register contains command bits that control the Intel® 6700PXH 64-bit PCI Hub behavior on
the PCI Express* bus.
Bits
Type
Reset
Description
15
RW
0
Bridge Configuration Retry Enable (BCRE): When set, the Intel® 6700PXH
64-bit PCI Hub is enabled to return a configuration retry response on the PCI
Express* bus for a configuration transaction to PCI/PCI-X.
14:12
RW
2h
Max_Read_Request Size (MRRS): Applies to the bridge segment when the
segment is in the PCI mode only. When in PCI-X mode, this does not apply
(branch predict). The Intel® 6700PXH 64-bit PCI Hub cannot send requests
greater than the size indicated by this field. Encodings are:
Value
000b
001b
010b
011b
100b
101b
110b
111b
Request Size
128 bytes
256 bytes
512 bytes
1024 bytes
2048 bytes
4096 bytes
Alias 101b
Alias 101b
11
RO
0
Enable No Snoop (ENS): This does not apply to the Intel® 6700PXH 64-bit
PCI Hub since it does not set the No Snoop bit on MSI transactions it
generates.
10
9
RO
RO
RO
RW
0
0
0
0
Auxiliary (AUX) Power PM Enable (AUXPWRPM_EN): The Intel® 6700PXH
64-bit PCI Hub ignores this since it does not support Aux Power.
Phantom Function Enable (PFE): The Intel® 6700PXH 64-bit PCI Hub
ignores this since it does not support Phantom functions.
8
Extended Tag Field Enable (ETFE): Always a 0 since the Intel® 6700PXH
64-bit PCI Hub only supports a 5-bit tag.
7:5
Maximum Payload Size (MPS): For Intel® 6700PXH 64-bit PCI Hub this
must be programmed to either 000 (128B) or 001(256B). Any other value will
default to a behavior of 128B.
4
RW
0
Reserved.
102
Intel® 6700PXH 64-bit PCI Hub Datasheet
INTEL [ INTEL ]
