From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp06.au.ibm.com ([202.81.31.148]:46527 "EHLO e23smtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751255Ab2D1IVo (ORCPT ); Sat, 28 Apr 2012 04:21:44 -0400 Received: from /spool/local by e23smtp06.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sat, 28 Apr 2012 08:16:32 +1000 Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q3S8LeiU32899196 for ; Sat, 28 Apr 2012 18:21:40 +1000 Received: from d23av04.au.ibm.com (loopback [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q3S8Ld0o013561 for ; Sat, 28 Apr 2012 18:21:40 +1000 Date: Sat, 28 Apr 2012 16:21:37 +0800 From: Richard Yang To: Bjorn Helgaas Cc: Richard Yang , linux-pci@vger.kernel.org Subject: Re: Does my understanding correct? Message-ID: <20120428082137.GB8402@richard> Reply-To: Richard Yang References: <20120427092704.GA22529@richard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-pci-owner@vger.kernel.org List-ID: On Fri, Apr 27, 2012 at 08:17:48AM -0600, Bjorn Helgaas wrote: >I assume your question relates to the Stratus ftServer topology. If >so, the lspci details might clarify things. > >In that system, my understanding is that 03:01.0 is a downstream port, >not an upstream port. > >I think your picture is slightly misleading because PCIe links are not >buses; they're point-to-point links between two devices. You've drawn >#3 and #5 as buses that can have several devices on them, which is not >really the case. The link from a downstream port should lead to >exactly one device. Hmm... if this is a PCI bridge, then it will have both internal bus and externel bus? or no internal pci bus, just one external bus? > >That's one thing that's strange in the ftServer topology: apparently >there are *two* devices on bus 03: the 03:00.0 upstream port and the >03:01.0 downstream port. I think 03:00.0 is the upstream port of a >PCIe switch, which is perfectly normal. My understanding is that >03:01.0 is another *downstream* port that leads to several more >devices (USB, NIC, etc). > >Bjorn -- Richard Yang Help you, Help me