Date: Thu, 8 Nov 2007 17:54:17 -0800 (PST)
From: Christoph Lameter <clameter@sgi.com>
To: "Zou, Nanhai" <nanhai.zou@intel.com>
cc: Mel Gorman <mel@skynet.ie>, LKML <linux-kernel@vger.kernel.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Greg KH <greg@kroah.com>, Dave Jones <davej@redhat.com>,
       Martin Ebourne <fedora@ebourne.me.uk>,
       "Siddha, Suresh B" <suresh.b.siddha@intel.com>, Andi Kleen <ak@suse.de>,
       Andrew Morton <akpm@linux-foundation.org>,
       Andy Whitcroft <apw@shadowen.org>
Subject: RE: [Patch] Allocate sparse vmemmap block above 4G
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On Fri, 9 Nov 2007, Zou, Nanhai wrote:

> > More magic values, both the 4GiB address here and the magic "1" at the
> > end are problems.
> > 
> Yes, the 4UL*1024*1024*1024 could be a define here.

The 4GB boundary here is MAX_DMA32_ADDRESS I guess? We are only having 
this problem because of the two DMA zones on x86_64. I thought Andi was 
getting rid of the first one at 16MB. If he would do so then ZONE_DMA 
could be used instead of DMA32 and everything will be fine.

For now you may want to put

#ifdef CONFIG_ZONE_DMA32

around this code since it depends on DMA32.
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