On 10/20/2014 05:50 AM, tiger...@via-alliance.com wrote:
> Hi, experts:
>
> I am studying Intel 64 and IA-32 Architectures Software Developer’s
> Manual Volume 3A.pdf .
>
> I have a few questions about Multi-processor management.
>
> 1.7.5 Multi-processor initialization In Chapter 7
>
> ……
>
> The mechanism for carrying out the MP initialization protocol differs
> depending on the IA-32 processor family, as follows:
>
> (1) For P6 family processors— The selection of the BSP and APs (see Section
> 7.5.1, “BSP and AP Processors”) is handled through arbitration on the
> APIC bus,
> using BIPI and FIPI messages. See Appendix C, “MP Initialization For P6
> Family
> Processors,”for a complete discussion of MP initialization for P6 family
> processors.
>
> (2) Intel Xeon processors with family, model, and stepping IDs up to F09H—
> The selection of the BSP and APs (see Section 7.5.1, “BSP and AP
> Processors”) is
> handled through arbitration on the systembus, using BIPI and FIPI messages
> (see Section 7.5.3, “MP Initialization Protocol Algorithm for Intel Xeon
> Processors”).
>
> (3) Intel Xeon processors with family, model, and stepping IDs of F0AH and
> beyond, 6E0H and beyond, 6F0H and beyond — The selection of the BSP and
> APs is handled through a special system bus cycle, without using BIPI
> and FIPI
> message arbitration (see Section 7.5.3, “MP Initialization Protocol
> Algorithm for Intel Xeon Processors”).
>
> So, current CPU(such as: bay trail ) uses method (2) or method (3) ?
For modern Xeons, it's all handled internally by the CPU hardware and
microcode. I don't believe BIOS needs to do anything, unless it wants
to change which socket contains the BSP. I don't know about Bay Trail;
your best bet would be to check Intel's BIOS Writer's Guide for that
platform, if you have access to it. (That's what they call it for Xeon;
I assume there's an equivalent for mobile.)
> 2.When to halt non-BSP cores in UEFI Code?
>
> Usually only BSP runs BIOS code.
> So when and where to halt non-BSP cores in UEFI Code?
> In CPU PEIM? Or SEC phase code?
That's a pretty platform-specific thing... servers try to initialize
multiple sockets in parallel, but that wouldn't be a consideration for
Bay Trail.
--
Brian Johnson
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