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  • Difference between PCIe host bridge and PCI-PCI bridge

    From Tan@21:1/5 to All on Fri May 26 11:15:36 2017
    Hi,

    I would appreciate if someone explains the difference between PCIe host bridge and PCI-PCI bridge on Intel platforms.

    On Intel systems, I see that there is only one Host Bridge and multiple PCI-PCI bridges. When I dump the config spaces, I found that PCI-PCI bridges have Header Type '1' while Host Bridge have header type '0'. As per my understanding, only non Bridge
    devices support header type '0'.

    Thanks,
    Tan

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  • From Clemens Ladisch@21:1/5 to Tan on Sat Jun 3 19:01:55 2017
    Tan wrote:
    I would appreciate if someone explains the difference between PCIe host bridge and PCI-PCI bridge on Intel platforms.

    PCI/PCI bridges are interfaces between two PCI buses.
    The host bridge (or root complex) is the interface between the top-level
    PCI bus and the CPU (the host).

    I found that PCI-PCI bridges have Header Type '1' while Host Bridge
    have header type '0'. As per my understanding, only non Bridge devices support header type '0'.

    From the point of view of the PCI bus, the host is not visible as a PCI
    device, so the device called "host bridge" is not actually a bridge.


    Regards,
    Clemens

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  • From Zihan@21:1/5 to All on Wed Feb 28 06:46:33 2018
    Nice explanation, but I wonder what is the situation when I have multiple PCI segment(domain)?

    Suppose I setup 3 PCI domains, do I have 3 Root Bridges in a single Host Bridge, or do I have 3 Host Bridges? In either case, do theses bridges share a common south bridge, or they have their own ones?

    Please correct me if I'm wrong as I just start to learn PCI(e).

    Thanks.

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