From: Richard Yang <weiyang@linux.vnet.ibm.com>
To: Richard Yang <weiyang@linux.vnet.ibm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>, linux-pci@vger.kernel.org
Subject: Re: Does my understanding correct?
Date: Sat, 28 Apr 2012 15:21:26 +0800 [thread overview]
Message-ID: <20120428072126.GB25916@richard> (raw)
In-Reply-To: <20120428050127.GA25916@richard>
On Sat, Apr 28, 2012 at 01:01:27PM +0800, Richard Yang wrote:
>On Fri, Apr 27, 2012 at 08:17:48AM -0600, Bjorn Helgaas wrote:
>>On Fri, Apr 27, 2012 at 3:27 AM, Richard Yang
>><weiyang@linux.vnet.ibm.com> wrote:
>>
>>I assume your question relates to the Stratus ftServer topology. If
>>so, the lspci details might clarify things.
>>
>Yes, my picture is a little bit related to your previous mail.
>While my intention is to find out how the physical world is represented
>in the kernel.
>
>Below is a typical topology in PCIe spec r3.0.
>
> +------------------+
> | |
> | RC |
> | Bus#0 |
> | ------------- |
> | |
> +-+-----+--------+-+
> 00:0.0 | | | 00:02.0
> +---------+---------+ | | | +------------+-------------+
> | +------+ | +-------| PCIe 2 PCI Bridge |
> | PCIe Endpoint | | | |
> +-------------------+ | | Bus#2 |
> | | -------------- |
> | +-------+---------------+--+
> | | |
> | 00:01.0 |02:00.0 |02:01.0
> +------------+-------------+ +-------+------+ +---+-------+
> | | |PCI dev | |PCI dev |
> | Switch | | | | |
> | Bus#1 | | | | |
> | --------------- | +--------------+ +-----------+
> | |
> +------------------------+-+
> | |
> | |
> | 01:00.0 | 01:01.0
> +---------+-------+ +--------+----------------+
> | | | |
> | PCI Endpoint | | PCIe Endpoint |
> | | | |
> | | | |
> +-----------------+ +-------------------------+
>
>Do you think the current assignment of bus number and pci_dev is
>correct?
>
BTW, if the chart is correct, 01:00.0 reprents Switch DownStream Port
or the PCI Endpoint?
>
>>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.
>>
>>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
--
Richard Yang
Help you, Help me
next prev parent reply other threads:[~2012-04-28 7:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-27 9:27 Does my understanding correct? Richard Yang
2012-04-27 14:10 ` Jiang Liu
2012-04-27 15:55 ` Bjorn Helgaas
2012-04-27 14:17 ` Bjorn Helgaas
2012-04-28 5:01 ` Richard Yang
2012-04-28 7:21 ` Richard Yang [this message]
2012-04-30 15:56 ` Bjorn Helgaas
2012-05-02 6:24 ` Richard Yang
2012-05-02 14:59 ` Bjorn Helgaas
2012-05-02 21:05 ` Don Dutile
2012-05-03 6:21 ` Richard Yang
2012-05-03 16:39 ` Bjorn Helgaas
2012-05-04 2:11 ` Richard Yang
2012-05-06 15:21 ` Richard Yang
2012-05-07 3:00 ` Richard Yang
2012-04-28 8:21 ` Richard Yang
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