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    SubjectRe: One problem in reassign pci bus number?
    From
    2012/4/24 Yinghai Lu <yinghai@kernel.org>:
    > On Sun, Apr 22, 2012 at 8:52 AM, Richard Yang
    > <weiyang@linux.vnet.ibm.com> wrote:
    >> 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?
    >
    > busn_alloc patchset should address your concern.
    >
    > git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git
    > for-pci-busn-alloc
    >
    hmm... the code changes too much...
    I need more time to understanding it.

    while the case i found is different from that reported by Don.

    > Yinghai
    > --
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    Richard Yang
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