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    SubjectRe: [solved] Yenta Cardbus allocation failure


    On Wed, 20 Dec 2006, Andrew Morton wrote:
    >
    > Linus has wondered "how much does Windows use"? How might we determine
    > that?

    Google knows everything, and finds, on MS own site no less:

    "Windows 2000 default resources:

    One 4K memory window

    One 2 MB memory window

    Two 256-byte I/O windows"

    which is clearly utterly bogus and insufficient. But Microsoft apparently
    realized this, and:

    "Windows XP default resources:

    Because one memory window of 4K and one window of 2 MB are not
    sufficient for CardBus controllers in many configurations, Windows XP
    allocates larger memory windows to CardBus controllers where possible.
    However, resource windows are static (that is, the operating system
    does not dynamically allocate larger memory windows if new devices
    appear.) Under Windows XP, CardBus controllers will be assigned the
    following resources:

    One 4K memory window, as in Windows 2000

    64 MB memory, if that amount of memory is available. If 64 MB is not
    available the controller will receive 32 MB; if 32 MB is not available,
    the controller will receive 16 MB; if 16 MB is not available, the
    bridge will receive 8 MB; and so on down to a minimum assignment of 1
    MB in configurations where memory is too constrained for the operating
    system to provide a larger window.

    Two 256-byte I/O windows"

    So I think we have our answer. Windows uses one 4k window, and one 64MB
    window. And they are no more dynamic than we are (we _could_ try to do it
    dynamically, but let's face it, it's fairly painful to dynamically expand
    PCI bus resources - you may need to reprogram everything up to the root,
    so it would be absolutely crazy to do that unless you have some serious
    masochistic tendencies).

    So let's just increase our default value to 64M too.

    Linus
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