From: Keith Owens <kaos@ocs.com.au>
To: Jan Engelhardt <jengelh@linux01.gwdg.de>
cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: HT not active 
In-reply-to: Your message of "Mon, 14 Aug 2006 13:38:22 +0200."
             <Pine.LNX.4.61.0608141335550.7970@yvahk01.tjqt.qr> 
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Date: Mon, 14 Aug 2006 22:10:25 +1000
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Jan Engelhardt (on Mon, 14 Aug 2006 13:38:22 +0200 (MEST)) wrote:
>Hello list,
>
>
>
>I cannot get HT to be used on some machine:
>
>w04a# cat /proc/cpuinfo 
>processor       : 0
>vendor_id       : GenuineIntel
>cpu family      : 15
>model           : 0
>model name      : Intel(R) Pentium(R) 4 CPU 1700MHz
>stepping        : 10
>cpu MHz         : 1694.890
>cache size      : 256 KB
>fdiv_bug        : no
>hlt_bug         : no
>f00f_bug        : no
>coma_bug        : no
>fpu             : yes
>fpu_exception   : yes
>cpuid level     : 2
>wp              : yes
>flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
>cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm up
>bogomips        : 3393.46
>
>'ht' indicates:
>#define X86_FEATURE_HT          (0*32+28) /* Hyper-Threading */                 
>
>so I installed an SMP kernel, which has
>CONFIG_SMP=y
>CONFIG_SUSPEND_SMP=y
>CONFIG_X86_FIND_SMP_CONFIG=y
>CONFIG_SCHED_SMT=y
>CONFIG_X86_HT=y
>
>yet it shows the 'up' flag in cpuinfo
>#define X86_FEATURE_UP          (3*32+ 9) /* smp kernel running on up */
>
>What could be missing? Some BIOS option perhaps?
>Thanks for any hints.

It could be BIOS HT settings.  You could also need CONFIG_ACPI, I have
seen HT systems which required ACPI before Linux could see the extra
threads.

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