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    SubjectRe: [PATCH] x86: provide a DMI based port 0x80 I/O delay override

    * Andi Kleen <andi@firstfloor.org> wrote:

    > > > The i8259 driver uses it and it is known to be needed on some old
    > > > chipsets. But it doesn't really have any "own" ports to use afaik.
    > >
    > > we'll solve that via an i8259-specific quirk. That is a lot cleaner
    > > and maintainable than the current generic, always-enabled "opt out"
    > > port-0x80 quirk.
    >
    > You mean using pci quirks + udelay? Will be probably challenging to
    > collect PCI-IDs for that. And there might be old systems needing it
    > without PCI. They likely won't have DMI either.
    >
    > In theory you could make it a DMI year cut off of course (and assume
    > old if no DMI, although that happens occasionally with new systems
    > too); but that is generally considered ugly.
    >
    > I don't think it's a big problem to keep delays of some form by
    > default in 8259 -- people who care about performance should be
    > definitely using APIC mode instead.

    do you remember which old systems/chipsets were affected by this
    problem? We had many - meanwhile fixed - PIC related problems, maybe
    it's a red herring and the delay just papered it over.

    Ingo


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