Re: APIC version and 8-bit APIC IDs

From: Martin Wilck
Date: Wed Aug 31 2005 - 09:28:08 EST


Hi Maciej,

It actually depends on the APIC type, rather than the CPU. E.g. with
Pentium systems the width of the ID is either 4 bits or 8 bits,
depending on whether the integrated or an external 82489DX APIC is
used. This should be able to be determined by the APIC version; for
v <= 0xf the ID is 8-bit and for v >= 0x10 it used to be 4-bit. Now
you only need to determine what is the value of v above 0x10 that
makes the ID 8-bit again.

That would be v>=0x14 for Intel. But that is wrong for AMD CPUs. The actual Dual-Core Athlon CPUs we have report an APIC version of 0x10. Please refer to the start of this thread.

Anyway, I understand that you agree this does not belong into the subarch code?

Regards
Martin

--
Martin Wilck Phone: +49 5251 8 15113
Fujitsu Siemens Computers Fax: +49 5251 8 20409
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