[PATCH v2 05/27] arm: pci: add a align_resource hook

[Bjorn Helgaas]

On Wed, Jan 30, 2013 at 4:47 AM, Thomas Petazzoni
<thomas.petazzoni at free-electrons.com> wrote:

> So what I'm going to do now is rework my patch series by removing the
> emulated host bridge (which is normally mandatory by PCIe standard, but
> Linux doesn't need it, so we don't care), ...

This is a tangent since you're removing the emulated host bridge
anyway, but it's been mentioned a couple of times, and I'd like to
understand this.  Jason mentioned earlier in the [07/27] emulated host
bridge thread that the PCIe spec requires a host bridge at 00:00.0.
I've never seen that mentioned in the spec; can somebody point me to
the actual requirement that host bridges appear in config space?

My understanding has been that host bridges, whether PCI or PCIe, are
required to *exist*, but that the way you enumerate them and configure
them is outside the scope of the PCI/PCIe specs.  I know that many
chips, especially for x86, *do* make the host bridge appear in config
space, but I've never seen a requirement for that.

Bjorn