linux-kernel - [x86_64] Question about early page tables initialization

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Message-ID: <87egq7dvwj.fsf@gmail.com>
Date:	Tue, 03 Feb 2015 18:25:32 +0600
From:	Alex Kuleshov <kuleshovmail@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: [x86_64] Question about early page tables initialization

Hello All,

I have a question about page tables initialization in the
arch/x86/boot/compressed/head_64.S

After we clear memory for page tables, there is code which
build PML4:

	leal	pgtable + 0(%ebx), %edi
	leal	0x1007(%edi), %eax      
	movl	%eax, 0(%edi)
        
Why there is offset 0x1007 instead just 0x7? 0x1007 is
4k + 7bit (PML4E) flags as i understand correctly. But
why we skip first 4k here?

Thank you.
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