42 Intel® 41210 Serial to Parallel PCI Bridge Developer’s Manual
Addressing
5.2 Secondary PCI Devices
Devices on the secondary PCI bus can be configured as private devices and hidden fr om BIOS a nd
host software. Devices are hidden by inhibiting the assertion of the IDSEL input of the device
during configuration cycles. This feature is configured through th e B I NIT regis t e r. Publ i c and private
devices are supported according to Table 20 .
5.3 Configuration-Space Access
The 41210 supports configuration-space accesses from PCI Express* using both the legacy PCI-to-
PCI Bridge Specification, Revision 2.3 access mechanism and the enhanced PCI Express*
configuration-space access mechanism. For local initialization, the 41210 also supports
configuration-pace accesses from the SMBus port and secondary PCI bus.

5.3.1 PCI Express* Configuration Access

The PCI-to-PCI Bridge Specification, Revision 1.1 defines the configuration-space region of a PCI
function to be up to 256 B. PCI Express* extends the PCI configuration space from 256B to 4 K.
The region up to 256 B can be accessed using the mechanism for configuration accesses defined in
the PCI-to-PCI Bridge Specification, Revision1.1. The region above 256 B is accessible only by
means of the enhanced configuration access mechanism defined in PCI Express*. This mechanism
utilizes a flat memory-mapped address region to access the configuration space. The core-logic
chipset converts the legacy PCI-to-PCI Bridge Specification, Revision1.1 or the enhanced PCI
Express* configuration-space accesses into PCI Express* configuration cycles.
Table 20. Seco ndary PCI Device Addressing
Device Number Signal Used for
IDSEL Input Public/Private Notes
0 AD16 Reserved Dedicated for bridge
1AD17
Public or Private Based on the device-hiding enable bit
(bit[2] of the BINIT register)
Available for secondary PCI devices
2AD18
3AD19
4AD20
5AD21
6AD22
7AD23
8AD24
Reserved
Used to address extended configuration
space of bridge
Based on the upstream-configuration
enable bit (bit[1] of the BINIT register)
9AD25
10 (0xA) AD26
11 (0x B) AD2 7
12 (0xC) AD28
Public Available for secondary PCI devices
13 (0xD) AD29
14 (0xE) AD30
15 (0xF) AD31