linux-kernel - Re: RFD: Should we remove the HLT check? (was Re: [PATCH 1/8] x86: avoid check hlt if no timer interrupts)

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Message-ID: <4BE48051.1060604@zytor.com>
Date:	Fri, 07 May 2010 14:04:17 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Arjan van de Ven <arjan@...ux.intel.com>,
	Jacob Pan <jacob.jun.pan@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, Alek Du <alek.du@...el.com>,
	Feng Tang <feng.tang@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Jacob Pan <jacob.jun.pan@...el.com>,
	Arjan van de Ven <arjan.van.de.ven@...el.com>
Subject: Re: RFD: Should we remove the HLT check?  (was Re: [PATCH 1/8] x86:
 avoid check hlt if no timer interrupts)

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

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