smp + acpi

smp + acpi

[Marco Berizzi]

Since 2.6.15 smp doesn't work anymore without ACPI
May be possible to have a note in "Symmetric multi processing
support" help dialog? Or is it possible to enable ACPI when
SMP is selected?

TIA

Re: smp + acpi

[Andi Kleen]

"Marco Berizzi" <pupilla@hotmail.com> writes:

> Since 2.6.15 smp doesn't work anymore without ACPI
> May be possible to have a note in "Symmetric multi processing
> support" help dialog? Or is it possible to enable ACPI when
> SMP is selected?

It's probably specific to your system, nothing general.

-Andi

Re: smp + acpi

[Marco Berizzi]

Andi Kleen wrote:

>"Marco Berizzi" <pupilla@hotmail.com> writes:
>
> > Since 2.6.15 smp doesn't work anymore without ACPI
> > May be possible to have a note in "Symmetric multi processing
> > support" help dialog? Or is it possible to enable ACPI when
> > SMP is selected?
>
>It's probably specific to your system, nothing general.

Hi Andi,

Thanks for the reply. I'm compiling linux on a pentinum
4 HT 3GHz. 2.6.14 did detect both processor, but all
kernels > 2.6.15 did not. (at least till 2.6.17.7)

Re: smp + acpi

[Robert Hancock]

Marco Berizzi wrote:
> Andi Kleen wrote:
> 
>> "Marco Berizzi" <pupilla@hotmail.com> writes:
>>
>> > Since 2.6.15 smp doesn't work anymore without ACPI
>> > May be possible to have a note in "Symmetric multi processing
>> > support" help dialog? Or is it possible to enable ACPI when
>> > SMP is selected?
>>
>> It's probably specific to your system, nothing general.
> 
> Hi Andi,
> 
> Thanks for the reply. I'm compiling linux on a pentinum
> 4 HT 3GHz. 2.6.14 did detect both processor, but all
> kernels > 2.6.15 did not. (at least till 2.6.17.7)

Are you sure you are really using the same configuration? HyperThreading 
has never worked without some amount of ACPI enabled.

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

RE: smp + acpi

[Brown, Len]

>> > Since 2.6.15 smp doesn't work anymore without ACPI
>> > May be possible to have a note in "Symmetric multi processing
>> > support" help dialog? Or is it possible to enable ACPI when
>> > SMP is selected?
>>
>>It's probably specific to your system, nothing general.
>
>Hi Andi,
>
>Thanks for the reply. I'm compiling linux on a pentinum
>4 HT 3GHz. 2.6.14 did detect both processor, but all
>kernels > 2.6.15 did not. (at least till 2.6.17.7)

CONFIG_ACPI=y is necessary to parse the ACPI tables
and discover HT siblings.  Except for the rare BIOS
that gives the option to enumerate HT via MPS
(thus breaking some versions of Windows),
enabling ACPI is the only way to enable HT.

Yes, in the distant past, CONFIG_ACPI=n did not remove
all ACPI code from your kernel, and that was a bug.

thanks,
-Len

Re: smp + acpi

[Andi Kleen]

> CONFIG_ACPI=y is necessary to parse the ACPI tables
> and discover HT siblings.  Except for the rare BIOS
> that gives the option to enumerate HT via MPS
> (thus breaking some versions of Windows),
> enabling ACPI is the only way to enable HT.
> 
> Yes, in the distant past, CONFIG_ACPI=n did not remove
> all ACPI code from your kernel, and that was a bug.

Ok thanks for the confirmation.

However the proposed change would be still wrong because
SMP can be without HT.

-Andi

RE: smp + acpi

[Brown, Len]

>> CONFIG_ACPI=y is necessary to parse the ACPI tables
>> and discover HT siblings.  Except for the rare BIOS
>> that gives the option to enumerate HT via MPS
>> (thus breaking some versions of Windows),
>> enabling ACPI is the only way to enable HT.
>> 
>> Yes, in the distant past, CONFIG_ACPI=n did not remove
>> all ACPI code from your kernel, and that was a bug.
>
>Ok thanks for the confirmation.
>
>However the proposed change would be still wrong because
>SMP can be without HT.

What proposed change?

I expect that the problem at hand is that CONFIG_SMP=y
is fine, but with CONFIG_ACPI=n, that isn't going to
find the HT threads on an HT system.

-Len