kernel/system can't see all 4G memory

George R Goffe grgoffe at
Thu Nov 3 16:13:48 UTC 2011


I grasp the concept of reserved memory but do not understand what it's used for or what the ramifications are.

Memory reserved from 4g for the driver?

Hmmm. It looks like that last value at the bottom goes up to 4g. Is this the culprit?

I'm not doing anything special with graphics... that I know of.

Here's what I get from your command.



grep 'BIOS-e820' /var/log/dmesg
[    0.000000]  BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
[    0.000000]  BIOS-e820: 000000000009f000 - 00000000000a0000 (reserved)
[    0.000000]  BIOS-e820: 00000000000d2000 - 00000000000d4000 (reserved)
[    0.000000]  BIOS-e820: 00000000000dc000 - 0000000000100000 (reserved)
[    0.000000]  BIOS-e820: 0000000000100000 - 00000000bfed0000 (usable)
[    0.000000]  BIOS-e820: 00000000bfed0000 - 00000000bfedf000 (ACPI data)
[    0.000000]  BIOS-e820: 00000000bfedf000 - 00000000bff00000 (ACPI NVS)
[    0.000000]  BIOS-e820: 00000000bff00000 - 00000000c0000000 (reserved)
[    0.000000]  BIOS-e820: 00000000f0000000 - 00000000f4000000 (reserved)
[    0.000000]  BIOS-e820: 00000000fec00000 - 00000000fec10000 (reserved)
[    0.000000]  BIOS-e820: 00000000fed00000 - 00000000fed00400 (reserved)
[    0.000000]  BIOS-e820: 00000000fed14000 - 00000000fed1a000 (reserved)
[    0.000000]  BIOS-e820: 00000000fed1c000 - 00000000fed90000 (reserved)
[    0.000000]  BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
[    0.000000]  BIOS-e820: 00000000ff800000 - 0000000100000000 (reserved)

"It's not what you know that hurts you, It's what you know that ain't so." Wil Rogers... Wil would say, "STIFF THE FED"!!!

From: Roberto Ragusa <mail at>
To: George R Goffe <grgoffe at>; Community support for Fedora users <users at>
Sent: Thursday, November 3, 2011 3:40 AM
Subject: Re: kernel/system can't see all 4G memory

On 11/03/2011 08:46 AM, George R Goffe wrote:
> Hi,
> My question is, am I missing something here?
> I upgraded my lenovo 60t to 4G memory and don't seem to be able to see all 4G of the upgrade.
> The hardware spec for this machine says it supports 4G memory.
> Any hints/clues/tips would be GREATLY appreciated.

x86_64, so something is happening at the hardware level (shared VGA?)
or BIOS level (wrong config, bugs).

What do you get with this command?

  grep 'BIOS-e820' /var/log/dmesg

it will show how the memory areas have been described by the BIOS.

   Roberto Ragusa    mail at
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