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To: "liyu@WAN" <liyu@ccoss.com.cn>
Cc: linux-kernel@vger.kernel.org
Subject: Re: one question about pgd allocation
References: <42C53E7D.7090404@ccoss.com.cn.suse.lists.linux.kernel>
From: Andi Kleen <ak@suse.de>
Date: 01 Jul 2005 15:15:43 +0200
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"liyu@WAN" <liyu@ccoss.com.cn> writes:
> 
>     I can not understand this. I search intel developer mannal. but
> nothing to help.
> Who can tell me why?

bit 0 is the present bit which needs to be set on the PGD, otherwise
the CPU will ignore it. A clearer way to write this would have been

        __pgd(__pa(pmd) | _PAGE_PRESENT)

-Andi