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

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Message-ID: <4FAA18F1.6080508@redhat.com>
Date:	Wed, 09 May 2012 09:12:49 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Jarkko Sakkinen <jarkko.sakkinen@...el.com>
CC:	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>, hpa@...ux.intel.com
Subject: Re: [PATCH 04/23] x86, realmode: Move reboot_32.S to unified realmode
 code

Il 08/05/2012 20:22, Jarkko Sakkinen ha scritto:
> +	xorl	%ecx, %ecx
> +	movl	%cr0, %edx
> +	andl	$0x00000011, %edx
> +	orl	$0x60000000, %edx
> +	movl	%edx, %cr0
> +	movl	%ecx, %cr3
> +	movl	%cr0, %edx
> +	andl	$0x60000000, %edx	/* If no cache bits -> no wbinvd */

Shouldn't this be a testl?

> +	jz	2f
> +	wbinvd
> +2:
> +	andb	$0x10, %dl

... because otherwise this is really a mov $0, %edx and it sounds wrong.
 It doesn't really matter, nobody really uses bit 4 of CR0 anymore,
still would be nice to fix it.

> +	movl	%edx, %cr0

Paolo
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