maximum of CPUs

John Baldwin jhb at
Mon Jul 14 14:49:57 PDT 2003

On 14-Jul-2003 Cagle, John (ISS-Houston) wrote:
> If you enable hyperthreading on an 8-way server, you'll end up with 16 logical processors (and a
> *whole bunch* of APIC's) -- a scenario that is not comprehended by FreeBSD.  In other words,
> there needs to be some more engineering done on FreeBSD to support more than 8 processors

Well, the problem is that the original APIC's only supported 15 physical
APIC IDs.  The (x)APIC's from Pentium4+ support 255 physical APIC IDs.
If the BIOS does the right thing as far as providing ID's for the I/O
APICs in the mptable and/or ACPI MADT, future versions of FreeBSD should
work just fine.


John Baldwin <jhb at>  <><
"Power Users Use the Power to Serve!"  -

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