mptable not showing all proccessors?

John Baldwin jhb at
Fri Apr 30 07:51:36 PDT 2004

On Thursday 29 April 2004 05:22 pm, Julian Elischer wrote:
> I have an intel server motherboard that has 2 Xeom HTT processors.
> FreeBSD correctly finds 4 processors but mptable only shows the 2
> physical processors.
> I assume this means the BIOS is buggy, as Hyperthreading is turned on
> in the BIOS and I assume it should have put all 4 in the table.
> Anyone seen anything like this?
> anything I should worry about?
>  FreeBSD 4.8++ seems to work on it just fin and sees all 4 cpus..
>  Would -current have any problems? I vaguely remember that -current
>  might trust the Bios tables a bit more..

MP Tables almost never show logical processors.  -current does a better job as 
it uses the MADT which does list logical processors.  -current's mptable code 
can be forced to assume that any logical processors are enabled (which is 
what 4.x does) via the 'MPTABLE_FORCE_HTT' kernel option.

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

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