linux-kernel - Re: [PATCH 04/23] x86, realmode: Move reboot

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Message-ID: <4FAA7C9A.2060808@linux.intel.com>
Date:	Wed, 09 May 2012 07:18:02 -0700
From:	"H. Peter Anvin" <hpa@...ux.intel.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
CC:	Jarkko Sakkinen <jarkko.sakkinen@...el.com>,
	linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
	Michal Marek <mmarek@...e.cz>, Sam Ravnborg <sam@...nborg.org>,
	Joseph Cihula <joseph.cihula@...el.com>,
	Shane Wang <shane.wang@...el.com>
Subject: Re: [PATCH 04/23] x86, realmode: Move reboot_32.S to unified realmode
 code

On 05/09/2012 07:15 AM, Paolo Bonzini wrote:
> 
> I'm not sure I understand.  The code has
> 
> 	andl	$0x60000000, %edx	; clear ET/PE
> 	jz	2f
> 	...
> 2:
> 	andb	$0x10, %dl		; clear CD/WT, %edx is always 0
> 
> 
> What I've suggested is:
> 
> 	testl	$0x60000000, %edx
> 	jz	2f
> 	...
> 2:
> 	andb	$0x10, %dl		; clear PE only
> 
> 
> What would jump to the BIOS with caches on is:
> 
> 	testl	$0x60000000, %edx
> 	jz	2f
> 	...
> 2:
> 	andl	$0x10, %edx		; Clear CD/WT/PE
> 
> 
> Am I missing something?
> 

Not awake yet, sorry...

	-hpa


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