linux-kernel - One problem in reassign pci bus number?

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Date:	Sun, 22 Apr 2012 23:52:02 +0800
From:	Richard Yang <weiyang@...ux.vnet.ibm.com>
To:	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: One problem in reassign pci bus number?

All,

I am reading the pci_scan_bridge() and not sure what will happen in
following situation.

Suppose the kernel is not passed the pci=assign-busses.

Below is a picture about the pci system.

                   +-------+       
                   |       | root bridge(0,255)
                   +---+---+       
                       |          Bus 0 
      -----+-----------+------------------------------+--
           |                                          |
           |                                          |
           |                                          |
      +----+----+                               +-----+-----+
      |         |  B1(1,15)                     |           |B2(16,28)
      +----+----+                               +-----+-----+
           |  Bus 1                                   |    Bus 16           
      -----+-----------------------         ----------+----------------
                            |
                       +----+----+
                       |         | B3               
                       +---------+                

Suppose B1 and B2 works fine with the BIOS, which get the right bus
number and range.

B3 does not works fine with the BIOS, which doesn't get the bus number.

So in pci_scan_bridge(), B3 will be met in the second pass and get bus
number 16?
Would this be a conflict?

-- 
Richard Yang
Help you, Help me

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