Re: [PATCH -v2] x86, pci: Handle fallout pci devices with peer rootbus

From: H. Peter Anvin
Date: Mon Jun 14 2010 - 16:09:19 EST

On 06/14/2010 01:00 PM, Bjorn Helgaas wrote:
>> the host bridges is on AMD CPUs,
> Don't confuse the HT host bridge with the PCI host bridge. The HT I/O spec
> is quite clear that it uses "host bridge" to refer to the HT host bridge,
> i.e., the interface between CPUs and a HyperTransport link.
> I agree that the *HT host bridge* is indeed on the AMD CPU. But that is
> certainly not the same as the PCI host bridge that bridges between an HT
> link and a PCI bus.
> See sections 4.9.4 (HT host bridge) and 7.4 (HT/PCI host bridge), for
> example.

>From a software point of view the latter is [largely] a PCI-to-PCI
bridge, though; it's not a root-level host bridge in the classical sense
(as noted in section 7.4).

Incidentally, in my copy of HT 3.10b, section 7.4 is marked
"HyperTransport Bridge Headers", and does not use the term "host bridge"
to refer to a secondary PCI bus. Section 4.9.4 is simply marked "Host
Bridge". As such, I think the HT spec is pretty consistent about
unambiguously referring to the HT host bridge when using the term "host


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at