Re: Linux v2.6.12-rc6

[Johannes Stezenbach <js@linuxtv.org>]

Bill Davidsen wrote:
> Johannes Stezenbach wrote:
> >Brice Goglin wrote:
> >>Johannes Stezenbach a écrit :
> >>>Indeed SMT works fine if I enable ACPI.
> >>>Is SMT without ACPI not supported?
> >>
> >>You can pass acpi=ht into the kernel command line to disable
> >>ACPI except the minimum required to get HT support.
> >
> >
> >That's nice, but I was thinking along the lines of:
> >
> >diff -ur linux-2.6.12-rc6.orig/arch/i386/Kconfig 
> >linux-2.6.12-rc6/arch/i386/Kconfig
> >--- linux-2.6.12-rc6.orig/arch/i386/Kconfig	2005-06-06 
> >23:16:27.000000000 +0200
> >+++ linux-2.6.12-rc6/arch/i386/Kconfig	2005-06-08 
> >13:35:08.000000000 +0200
> >@@ -503,7 +503,7 @@
> > 
> > config SCHED_SMT
> > 	bool "SMT (Hyperthreading) scheduler support"
> >-	depends on SMP
> >+	depends on SMP && ACPI
> > 	default off
> > 	help
> > 	  SMT scheduler support improves the CPU scheduler's decision making
> >
> >Comments? Is this intended?
> 
> I would think that you can't do HT without ACPI, so there's no point in 
> building in HT scheduling unless you can have HT.
> 
> Is that what you were asking? I was hoping someone else would comment.

In 2.6.12-rc5 SMT worked without CONFIG_ACPI. (IIRC the kernel used some
minimal ACPI stuff anyway for CPU initialisation).

I don't use power management or other features of ACPI so I
had it disabled, and my build broke with 2.6.12-rc6.

Johannes