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Message-ID: <ac8af0be0804090204t79beaca2qe077a28fc4a515ad@mail.gmail.com>
Date: Wed, 9 Apr 2008 17:04:24 +0800
From: "Zhao Forrest" <forrest.zhao@gmail.com>
To: "Andi Kleen" <andi@firstfloor.org>
Subject: Re: Does Linux have plan to support memory hole remapping?
Cc: discuss@x86-64.org, linux-kernel@vger.kernel.org, yhlu.kernel@gmail.com,
       mingo@elte.hu, ak@suse.de
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On 4/9/08, Andi Kleen <andi@firstfloor.org> wrote:
> "Zhao Forrest" <forrest.zhao@gmail.com> writes:
> >
> > As we can see from above information that the physical memory in system
> > is 32768MB(32GB). However OS is only using about
> > (32768-512)MB(MemTotal:     33010240 kB). Does this mean that this
> > linux kernel can't use the physical memory remapped
> > from (4G-512M, 4G) to (32G, 32G+512M)?
>
> The linux kernel can only use the memory passed to it by the BIOS.
> Sometimes they need special BIOS setup options to enable remapping. If
> there are no such options and you can't upgrade it you're out of luck

Yes, I have enabled mem hole remapping in BIOS SETUP.
After looking into dmesg, I found that all 32GB physical memory has
been allocated to 8 nodes, but why MemTotal shows a less amount of
memory than 32GB? Interesting......
Does MemTotal means the amount of physical memory allocated to all
nodes? Or it has different meanings?

Thanks,
Forrest