Subject: Re: [Bug] 2.6.18-rc6-mm2 i386 trouble finding RSDT in
	get_memcfg_from_srat
From: Dave Hansen <haveblue@us.ibm.com>
To: vgoyal@in.ibm.com
Cc: keith mannthey <kmannth@us.ibm.com>, lkml <linux-kernel@vger.kernel.org>,
       ebiederm@xmission.com, andrew <akpm@osdl.org>
In-Reply-To: <20060914230442.GE25044@in.ibm.com>
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Date: Thu, 14 Sep 2006 16:21:33 -0700
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On Thu, 2006-09-14 at 19:04 -0400, Vivek Goyal wrote:
> I think I know what is going on wrong here. boot_ioremap() is assuming 
> that only first 8MB of physical memory is being mapped and while
> calculating the index into page table (boot_pte_index) we will truncate
> any higher address bits. 

Vivek, are those pte pages still all contiguous?

Yeah, that's probably it.  Keith, I'm trying to think of reasons why we
need the mask here:

#define boot_pte_index(address) \
             (((address) >> PAGE_SHIFT) & (BOOT_PTE_PTRS - 1))

and I can't think of any other than just masking out the top of the
virtual address.  You could do this a bunch of other ways, like __pa().

This might just work:

static unsigned long boot_pte_index(unsigned long vaddr)
{
	return __pa(vaddr) >> PAGE_SHIFT;
}

-- Dave

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