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SubjectRe: [PATCH 4/8] PCI: Add quirk to disable MSI support for Amazon's Annapurna Labs host bridge
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On Sun, 2019-07-14 at 15:09 +0000, Chocron, Jonathan wrote:
> > s/host bridge/Root Port/, if I understand correctly.
> >
>
> Ack.
>
> BTW, what is the main difference between the 2 terms, since they seem
> to be (mistakenly?) used interchangeably?

The host bridge is the parent of the root port. You can have several
root ports under a host bridge in fact. They tend to be part of the
same silicon and somewhat intimately linked but they are distinct
logical entities. The root port appears as a PCIe p2p bridge sitting on
the top level bus provided by the host bridge. The Host Bridge doesn't
have to have a representation in config space (it sometimes does
historically, but as a sibling of the devices on that top level bus. In
PCIe land, these are chipset built-in devices).

Ben.


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