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    SubjectRe: Hot PCI bus plugging

    Reading this thread with much interest I just have to think how much
    effort it is a least to get a minimal hot swapping support up and

    The thoughts I have are, that at the beginning only a modified kernel
    is needed, that would allow to retrigger the PCI scanning at any
    time. Nothing automatic is done further, the current PCI configuration
    is just recorded.

    Then it should be possible to insmod standard drivers. They won't see
    any difference between a card that was active at system start, and a
    card that was later inserted and added to the system by a rescan of
    the bus.

    If you want to unplug the card you would have to remove the module
    manually before unplugging, to prevent that the driver crashes badly.

    A PCI bus rescan would then remove that PCI card from the kernel list,
    preventing accidently loading a driver for a not more existing
    card. It's not strictly necessary therefore, if you know, what you are
    doing, I think.

    Is this all, that is needed to get it work? It wouldn't be very user
    friendly of course, but a experienced user surely could handle this
    and therefore could help in the developing process by adding

    If this concept fits, the big question is: How much effort is it to
    add the rescanning to the PCI code of the kernel.

    Thinking about lots of badly designed hardware, I wouldn't wonder that
    just detecting properly the installed PCI cards in a rescan could give
    lots of headaches.

    Lets quote
    * Eric Lowe ( [991122 17:50]:
    > In the current implementation, it (pci.c) scans for all devices at boot time.
    > I don't think it would be a big deal to modify the kernel to support hot-plug
    > devices, though there should probably be a notification mechanism set up so
    > that drivers are notified cleanly when the device has been (or is about to
    > be) removed.

    Maybe it isn't as hard as I think?

    Btw: I guess some user level programs will happily crash, when
    the contents of /proc/pci change, but that is another topic.

    * Eric Lowe
    > I may work on this if there is enough demand for it.

    Do you need assistance, hint, hint?


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