Hi, I used to think that head host bridge / PCI controller is a domain in itself. No? Thanks, Rajat > -----Original Message----- > From: Matthew Wilcox [mailto:matthew@xxxxxx] > Sent: Friday, February 19, 2010 6:24 PM > To: Rajat Jain > Cc: linux-pci@xxxxxxxxxxxxxxx > Subject: Re: PCI bus numbering in a system with multiple PCI controllers > > On Fri, Feb 19, 2010 at 04:49:13PM +0530, Rajat Jain wrote: > > Assuming the firmware has not done any PCI bus enumeration in a system > > with 2 PCI controllers, I want to know if PCI bus numbering done by > > Linux WILL have bus numbers repeated (among the 2 PCI trees). > > > > For instance: > > > > 1) Will the bus emanating from both the PCI bus controllers have PCI bus > > no 0 (although they will have different PCI domain numbers). > > That's up to the hardware / firmware involved. > > For example, large HP Itanium systems have multiple IO chassis. > Each chassis contains around 8 PCI host bridges, which may be numbered > along these lines: > > 0x00 > 0x20 > 0x40 > 0x60 > 0x80 > 0xa0 > 0xc0 > 0xe0 > > So there will not be duplication of PCI bus numbers if you have only one > chassis, despite there being multiple PCI root bridges. When you plug > in a second chassis, the same bus numbers exist in that chassis too, > and the only way to distinguish between them is by domain number. > > I believe other high-end systems operate in much the same manner. > > -- > Matthew Wilcox Intel Open Source Technology Centre > "Bill, look, we understand that you're interested in selling us this > operating system, but compare it to ours. We can't possibly take such > a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
