Motherboard Forums


Reply
Thread Tools Display Modes

PCI Bus Enumeration

 
 
John Flynn
Guest
Posts: n/a
 
      01-26-2004, 11:55 AM
Could someone explain to be what is meant by the phrase "PCI
Enumeration"? I think that it has something to do with initialising
the PCI bus and devices.

How is this done by a BIOS or the Operating System. What if you are
not running with an OS what happens to the PCI devices and does
enumeration still take place?

What effect has a PCI bridge or a Compact PCI bridge have on the
Enumeration process?

Obviously, if there are webpages out there that has this information
then point me to them. My question is not related to any specific
Operating System (Windows or Linux) it is just a general question.

Thanks,
J
 
Reply With Quote
 
 
 
 
daytripper
Guest
Posts: n/a
 
      01-27-2004, 02:17 AM
On 26 Jan 2004 03:55:34 -0800, (E-Mail Removed) (John Flynn) wrote:

>Could someone explain to be what is meant by the phrase "PCI
>Enumeration"? I think that it has something to do with initialising
>the PCI bus and devices.
>
>How is this done by a BIOS or the Operating System. What if you are
>not running with an OS what happens to the PCI devices and does
>enumeration still take place?
>
>What effect has a PCI bridge or a Compact PCI bridge have on the
>Enumeration process?
>
>Obviously, if there are webpages out there that has this information
>then point me to them. My question is not related to any specific
>Operating System (Windows or Linux) it is just a general question.
>
>Thanks,
>J


Enumeration is the process of hunting for every possible PCI agent, usually
using Config (Space) Reads to the Device/Vendor ID register address (a dword
at x00h), while stepping the IDSEL addresses (bits 31:11 on each bus segment).

Only one device on any segment can be accessed with any single IDSEL, and if a
device does not respond to the Config Read (ie: a Master Abort occurs) the
enumeration process interprets this to mean there is no device behind the
currently tested IDSEL, and moves on to the next.

Bridges merely require that the original transaction be formatted to pass
through the bridge to the subordinate segment (and as bridged segments can
also have bridged subordinate segments, to even more hierarchically
subordinate segments).

If you have access to a PCI Bus spec or any decent book on the architecture,
check out the difference between a Type 0 and Type 1 Configuration access.

cheers

/daytripper
 
Reply With Quote
 
 
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Abit NF7s v2.0: PCI bus speed tied to AGP bus? pigdos Abit 5 02-17-2006 07:17 PM
Problem with USB enumeration... -> now with link to CATC trace... Martin Maurer Embedded 0 08-13-2005 09:22 AM
USB enumeration Graeme Embedded 0 06-15-2004 10:11 AM
PCI Bus -Retrieving Bus Utilization Values Dada IBM 1 01-20-2004 05:40 AM
bayone avi plus enumeration failed dk Soyo 0 11-23-2003 02:00 AM


All times are GMT. The time now is 05:08 AM.


Welcome!
Welcome to Motherboard Point
 

Advertisment