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I'm trying to learn about how pci drivers works in Linux in PC environment but really find it difficult to go thorugh.There are few following statement which I like to understand before make a move.

  1. The PCI specification permits a system to host up to 256 buses.(buses = pci slots?)

  2. Each bus hosts up to 32 devices.

  3. Each device can be a multifunction board with a maximum of eight functions.(what exactly this line means?)

On my PC can see only three pci slots (are these are called buses) and from each slots one irq lines is directed to cpu.

It seems my understanding is quite wrong and thats why wanted to get in more views in.

Amit Singh Tomar
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1 Answers1

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I can answer at least part of your question.

 C1  C2  C3  ....  Chipset/PCI bridge
 |   |    |            |
 +---+----+  .... -----+

C1, C2, C3 etc are the white PCI connectors.
This is where you plug in a PCI card. These are often called PCI slots

The line at the bottom is the PCI bus.
All devices on the same PCI bus can directly communicate with eachother.
Since they are on a shared bus, only one device can be active at the same time.


The part I marked Chipset/PCI bridge is often where the PCI bus is connected to other parts of the computer. This can be a connection to the chipset, or another PCI bus.


I found some link on Ars Technica's archives which might help:
http://archive.arstechnica.com/paedia/p/pci-express/m-pcie-1.html
http://archive.arstechnica.com/paedia/p/pci-express/m-pcie-2.html
...

Hennes
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  • Thanks Hennes for your Kind response ,one thing would like to ask here is Pci bride is nothing but PCI controller? and Could you please lighten up a bit about how irq lines are mappaed from pci to cpu? – Amit Singh Tomar Dec 19 '12 at 10:24
  • I am not sure I can answer that without an epic long answer. It is probably best to read a few articles and then come back with specific questions. – Hennes Dec 19 '12 at 10:46
  • Thnaks Hennes ,would you like to suggest some good docs which I can go through . – Amit Singh Tomar Dec 19 '12 at 10:55
  • Not really. Everything seems to be outdated or behind paywalls :( – Hennes Dec 19 '12 at 11:53
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    Mindshare also has very good, comprehensive books on various technologies, in particular, legacy PCI and PCIe. This one for example[PDF-partial ebook] https://www.mindshare.com/files/ebooks/PCI%20Express%20System%20Architecture.pdf Definitely worth buying if you'll be doing a lot of work in PCI. – penguin4hire Apr 21 '16 at 00:16