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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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