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Date: Fri, 07 May 2010 14:04:17 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Linus Torvalds <torvalds@linux-foundation.org>
CC: Arjan van de Ven <arjan@linux.intel.com>,
       Jacob Pan <jacob.jun.pan@linux.intel.com>,
       Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
       Alek Du <alek.du@intel.com>, Feng Tang <feng.tang@intel.com>,
       LKML <linux-kernel@vger.kernel.org>,
       Jacob Pan <jacob.jun.pan@intel.com>,
       Arjan van de Ven <arjan.van.de.ven@intel.com>
Subject: Re: RFD: Should we remove the HLT check?  (was Re: [PATCH 1/8] x86:
 avoid check hlt if no timer interrupts)
References: <1273254108-3234-1-git-send-email-jacob.jun.pan@linux.intel.com> <1273254108-3234-2-git-send-email-jacob.jun.pan@linux.intel.com> <4BE478C1.2060602@zytor.com> <4BE4791B.1060304@linux.intel.com> <alpine.LFD.2.00.1005071354310.901@i5.linux-foundation.org>
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On 05/07/2010 01:54 PM, Linus Torvalds wrote:
> 
> 
> On Fri, 7 May 2010, Arjan van de Ven wrote:
> 
>> On 5/7/2010 13:32, H. Peter Anvin wrote:
>>>
>>> I really wish I knew the exact systems affected by the HLT bug.  If I
>>> remember correctly, it was some 386 systems -- or possibly 486 systems
>>> as well -- a very long time ago.  This test just provides a diagnosis if
>>> the system really is bad (it hangs with an obvious message) at the cost
>>> of some 40 ms to the system boot time.  I suspect C1 (HLT) being broken
>>> is not anywhere close to the predominant power management problem in the
>>> current day, and as such I'm wondering if this particular test hasn't
>>> outlived its usefulness.
>>>
>>> Thoughts?
>>
>> we could at least hide it behind the "don't run on pentium or newer" config
>> options..
> 
> Ack. That would take care of all relevant machines.
> 

Sounds like a plan.  Jacob, do you want to submit a new patch (bypassing
this check if boot_cpu_info.x86 >= 5)?

	-hpa