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Subject: Re: PROBLEM: BAD RAM SIZE DETECTION ON DELL POWER EDGE SC420
From: Arjan van de Ven <arjan@infradead.org>
To: cyril canovas <cyril@egnx.com>
Cc: linux-kernel@vger.kernel.org
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Date: Thu, 01 Jun 2006 16:29:19 +0200
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> BIOS-provided physical RAM map:
>  BIOS-e820: 0000000000000000 - 00000000000a0000 (usable)
>  BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved)
>  BIOS-e820: 0000000000100000 - 00000000d768cc00 (usable)

and ...
>  BIOS-e820: 00000000d768cc00 - 00000000d768ec00 (ACPI NVS)
>  BIOS-e820: 00000000d768ec00 - 00000000d7690c00 (ACPI data)
>  BIOS-e820: 00000000d7690c00 - 00000000d8000000 (reserved)
>  BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved)
>  BIOS-e820: 00000000fec00000 - 00000000fed00400 (reserved)
>  BIOS-e820: 00000000fed20000 - 00000000feda0000 (reserved)
>  BIOS-e820: 00000000fee00000 - 00000000fef00000 (reserved)
>  BIOS-e820: 00000000ffb00000 - 0000000100000000 (reserved)
... this is where your memory is going. The bios seems to have reserved
it in part for itself, and in part for PCI mmio space...
(which is required to have pci at all). Some machines remap this
quarter-to-half a gig (half on your machine) to above the 4Gb mark.
Your machine does not.