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    SubjectRe: PnP model
    On Mon, Feb 03, 2003 at 08:43:25PM +0000, Adam Belay wrote:
    > In many cases, Auto configuration can be better then manual configuration.
    > 1.) The auto configuration engine in my patch is able to resolve almost any
    > resource conflict and provides the greatest chance for all devices to have
    > resources allocated.

    There is a nice problem with ISA PNP serial ports generated by this
    type of thing in 2.5.59.

    On boot, we probe for the usual serial ports, and discover two at
    0x3f8 and 0x2f8, and we request these resources. Please note that
    one port could be in use as a serial console from earlier in the

    Then, we move on to the PNP probes. The PNP layer gives us two
    serial ports, and we initialise them. The PNP layer notices that
    the resources for 0x3f8 and 0x2f8, and re-assigns the ports to
    0x3e8 and 0x2e8. The serial layer finds two extra ports at
    0x3e8 and 0x2e8.

    However, the ports at 0x3f8 and 0x2f8 are now gone, along with the
    serial console, and the boot messages claim that we have four serial
    ports at ttyS0, ttyS1, ttyS2, and ttyS3, when the machine in fact
    only has two serial ports. The serial layer likewise believes we
    have four serial ports.

    I look forward to your thoughts on getting around this problem.

    Russell King ( The developer of ARM Linux

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