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Date: Sat, 10 Jul 2010 14:37:01 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Cyrill Gorcunov <gorcunov@gmail.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>, x86@kernel.org,
       linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
       Yinghai Lu <yinghai@kernel.org>
Subject: Re: [PATCH v2] x86: Early-boot serial I/O support
References: <1278790820-1817-1-git-send-email-penberg@cs.helsinki.fi> <20100710210750.GC6615@lenovo>
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On 07/10/2010 02:07 PM, Cyrill Gorcunov wrote:
> On Sat, Jul 10, 2010 at 10:40:20PM +0300, Pekka Enberg wrote:
>> This patch adds serial I/O support to very early boot printf(). It's useful for
>> debugging boot code when running Linux under KVM, for example. The actual code
>>  
>> +#define cpu_relax()	asm volatile("rep; nop" ::: "memory")
>> +

We don't need "memory" here since the early boot environment is
single-threaded.

	-hpa


-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.