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INT 15.87 in protected mode (Developers)

posted by bretjohn Homepage E-mail, Rio Rancho, NM, 09.09.2011, 00:31

> Good luck. I guess it may not be easy task - would be required
> interpretation of ACPI AML? I don't know but I'm interested. In my case the
> interest leading me to ACPI was that I cannot determine real number of CPU
> cores and from what I read it's needed to parse some ACPI tables to get
> this info. CPUID is useless in this way because it reports some maximum of
> cores for whole family not specific CPU. Intel can disable some cores and
> sell it for lower price but CPUID data is not updated...
There are two "parts" to ACPI. Part of it is stored in fixed-format tables, and part of it is more "free-form" (this includes the AML part). Nothing in ACPI is trivial, but the fixed-format part is not too difficult to wade through. The details on how to change the CPU duty cycle and how to shut down the computer are in the fixed-format part.

The "free-form" part is another matter altogether. AML in particular is EXTREMELY nasty. Unfortunately, determining the number of CPU's must be done by parsing the free-form part, though it is not AML, so I think it could be done without too much difficulty (famous last words, since I've never actually done it). It's definitely not as easy as figuring out how to shut down the computer.

The other thing to keep in mind is that at least some computers store bogus information in ACPI, so you can't necessarily believe what it tells you.

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