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Subject: SPARSEMEM, HIGHMEM and the SMP8634
From: "Ed Okerson" <>
Date: Fri, 12 Dec 2008 10:16:08 -0600
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I am having great difficulty trying to get memory allocation from
DRAM1 on the Sigma SMP8634.  It seems that some hybrid between
SPARSEMEM and HIGHMEM would be needed.  I have read all the previous
threads on this topic, but it appears no one has been successful yet.

I am working with the kernel (latest release from Sigma).
At this point, I have it kinda recognizing the memory:

On node 0 totalpages: 31712
  DMA zone: 1024 pages used for memmap
  DMA zone: 0 pages reserved
  DMA zone: 22496 pages, LIFO batch:3
  Normal zone: 0 pages used for memmap
  HighMem zone: 256 pages used for memmap
  HighMem zone: 7936 pages, LIFO batch:0
Built 1 zonelists.  Total pages: 30432

But the memory output from the end of mem_init() does not show it:

Memory: 82432k/94080k available (2856k kernel code, 11604k reserved,
468k data, 5932k init, 0k highmem)

On the kernel command line I am passing:

mem=92M mem=32M@0x26000000

Which, as I understand it, should give me 32M out of the bottom of the
128M on bank DRAM1.  The output of 'free' also does not indicate any
more memory than if I just pass 'mem=92M' to the kernel.

So what needs to be done to get the high memory added to usable
memory?  I think I have gone beyond my understanding of memory
management.  If the memory is in fact available, how can I tell, and
how can it be allocated for user space programs?

Ed Okerson

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