Re: [PATCH v2] x86: Early-boot serial I/O support

From: H. Peter Anvin
Date: Sat Jul 10 2010 - 17:38:04 EST


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.

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