Intel has a web page dedicated to ACPI. Have you seen this link? http://developer.intel.com/technology/iapc/acpi/
I'm not sure which OS you're working with, but I found a link to an old microsoft whitepaper that includes an explanation of P_BLK with regards to "Supporting Intel SpeedStep Technology using ACPI 2.0 Objects." Check out the following link starting at page 12 to see if it is of any help to you: http://download.microsoft.com/download/5/7/7/577a5684-8a83-43ae-9272-ff260a9c20e2/Windows%20Native%20Processor%20Performance%20Control.doc
If this document is any help, you may also check out the other Microsoft whitepapers linked here: http://search.microsoft.com/Results.aspx?qsc0=0&q=+%28P_BLK%29+&mkt=en-US&FORM=QBME1&l=1
On page 11 of the Intel® Celeron® Mobile Processor Dual-Core T1x00 datasheet, in the Low Power Features section, you'll find some information P-BLK.
The "Low Power Features" sections of the following Intel mobile processor datasheets also contain informatin on P_BLK:
I would like to know how to locate that register block (P_BLK). Not how to use it (by now).
I saw intel and ACPI web page (acpi.info). I downloaded the specification from last one.
There is a register block (P_BLK) that is used to throttling the cpu performance, it is described in the section 126.96.36.199 Processor Register Block at page 76 of the revision 3.0b of the specification, but there is not a pointer in the tables to access it, as other registers have. The datasheets of the processors tell what I can do with P_BLK registers but not how to locate it. I can not find how to access it.
I am working at a low level programing (C) read/writing into the registers, not the specification's ASL or AML. And I am starting with the acpi component architecture (ACPICA), but I do not found the throttling configuration in it.
The OS I am working with is MaRTE OS (http://marte.unican.es), a Hard RTOS with a Minimal RT POSIX.13 subset.
I don't personally have the programming background expertise you're looking for. I have asked around my circle of peers and contacts for assistance but haven't found anyone yet who can answer your question. I would suggest posting your question(s) on the Intel Software Network communities: http://software.intel.com/en-us/multi-core/ as well to see if you have any more luck finding an answer. Sorry for the run around. Good luck.