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INT 15.87 in protected mode (Developers)

posted by bretjohn Homepage E-mail, Rio Rancho, NM, 09.09.2011, 20:09

> Well, could you tell me e.g. what can I read from fixed tables about
> modifying CPU duty cycle? How ACPI describe it? Will I read some IO port
> address or memory address and description what data to write in? I though
> that you have to run AML code for that but if not then it would be
> easier...
Well, I reviewed some of my code again (it's been a long time since I worked on the program), and I mis-spoke. In both cases (shutting down and changing the duty cycle), only half of what you need is in the fixed-format part, and the other half is in the free-form part. Bad memory on my part -- sorry about that.

I'll still privately send you the code and the program if you want it. I think you could modify it to determine the number of CPU's without too much difficulty, since it already goes partially into one of the CPU sections to do the duty cycle calculations. You can also look at FDAPM for info on this.

> I'll see. ACPI spec has many many pages... :P
Indeed it does. It's actually a really ugly spec -- very difficult to understand, even more difficult to implement.

> Yes, also windows and linux denied to use ACPI on some old PC but I belive
> it's clean now.
I would be really surprised if all modern computers are all perfectly "clean", but they may be better than they were. I find modern hardware generally less compliant with standards than older hardware, not more compliant (especially in the USB world).

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