> Hmm, I think they're pretty much the same, see also below. As I
> understand it, "PCI host bridge" == "PCI-to-${whatever} bridge
> that on given system is used to configure the PCI bus" (eg. initiates
> configuration cycles for given segment).

Well, I know they are the same physical device. I said they are
different views on autoconf(9). On most port the name of pchb(4) is
used to attach PCI-HOST bridge during configuring PCI bus,
i.e. all pchbmatch() functions found in
 sys/arch/amd64/pci/pchb.c
 sys/arch/bebox/pci/pchb.c
 sys/arch/cobalt/pci/pchb.c
 sys/arch/i386/pci/pchb.c
 sys/arch/ibmnws/pci/pchb.c
 sys/arch/macppc/pci/pchb.c
 sys/arch/mvmeppc/pci/pchb.c
 sys/arch/pmppc/pci/pchb.c
 sys/arch/prep/pci/pchb.c
 sys/arch/sandpoint/pci/pchb.c
check PCI_CLASS and PCI_SUBCLASS, or PCI_VENDOR and PCI_PRODUCT
(and do nothing other than print product info in pchbattach() BTW).

On the other hand, some of these ports also configure these bridge
devices at mainbus:
 sys/arch/alpha/pci/{apecs,cia,irongate,lca,dwlpx,mcpcia}.c
 sys/arch/cobalt/dev/gt.c
 sys/arch/macppc/pci/{bandit,grackle,uninorth}.c
 sys/arch/pmppc/cpc_mainbus.c
while some other ports don't have specific sources (i.e. pci bus
is attached at mainbus directly), maybe because they are
initialized by firmware or have no pchb variants so there
is few thing to be done by OS during autoconf, I think.

On some ports have both "pchb* at pci?" and "pci* at pchb?"
but it seems wrong, IMO.
---
Izumi Tsutsui