On Wed, 20 Nov 2002, Arjan van de Ven wrote:
> On Wed, Nov 20, 2002 at 12:53:04PM +0000, Hugh Dickins wrote:
> >
> > I know too little to comment definitively, but it's my understanding
> > that a dual HT machine should only show 2 processors in its MP table,
> > their siblings only appearing through analysis of the ACPI tables.
> >
> > Whether it's that your MP table has been wrongly set up, or that
> > you've really been given 4 processors when you only asked for 2
> > (sue your supplier!), I cannot say. I've copied Jun at Intel
> > and Arjan at RedHat, and hope they can shed more light on this.
>
> Linux has zero problem with a sane MP table that lists all
> CPU's. Intel normally seems to recommend against it (maybe N3.51 doesn't
> like it or so) but it's all fair as far as I'm concerned.
> The bios is supposed to offer you a choice
> to disable hyperthreading, use that ;)
>
Sure, the bios has this option (and it works). I just believed the 'noht'
option would disable it from a kernel perspective. I understand that if
the MP table lists 4 processors, the kernel must think it is 4 processors
and enable them. But what is the purpose of the 'noht' option ? If it is
to avoid scanning the ACPI table for CPUs, wouldn't it be less confusing
to call it something like 'acpismp=disable', since you apparently can't
disable the siblings anyway (when they are also listed in the MP table) ?
Regards,
--
Steffen Persvold | Scali AS
mailto:sp@scali.com | http://www.scali.com
Tel: (+47) 2262 8950 | Olaf Helsets vei 6
Fax: (+47) 2262 8951 | N0621 Oslo, NORWAY
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