From: Eric Dumazet <dada1@cosmosbay.com>
To: Mike Richards <mrmikerich@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Missing RAM on x86_64
Date: Sat, 02 Jun 2007 10:51:12 +0200 [thread overview]
Message-ID: <46612F80.2070906@cosmosbay.com> (raw)
In-Reply-To: <516d7fa80706012151m32facb87nafb68811c784fa54@mail.gmail.com>
Mike Richards a écrit :
> Hi, I appear to be missing quite a bit of RAM on an x86_64 system. I
> have 1GB installed, but 'free' only shows 878MB:
>
> pokey$ free -m
> total used free shared buffers cached
> Mem: 878 571 306 0 52 332
> -/+ buffers/cache: 186 691
> Swap: 1023 0 1023
>
> I'm used to seeing a little bit of RAM missing with 32bit systems, but
> 146MB seems a bit much. The part of dmesg that concerns the RAM is
> shown below. Anyone know what's up here? Is this normal for an x86_64
> system?
>
> Linux version 2.6.20.11 (root@pokey) (gcc version 4.1.2) #1 SMP Thu
> May 24 18:29:52 GMT 2007
> Command line: auto BOOT_IMAGE=2.6.20.11 rw root=801
> BIOS-provided physical RAM map:
> BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
> BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
> BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved)
> BIOS-e820: 0000000000100000 - 0000000037fd0000 (usable)
> BIOS-e820: 0000000037fd0000 - 0000000037fde000 (ACPI data)
> BIOS-e820: 0000000037fde000 - 0000000038000000 (ACPI NVS)
> BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
> BIOS-e820: 00000000fee00000 - 00000000fef00000 (reserved)
> BIOS-e820: 00000000ff780000 - 0000000100000000 (reserved)
I would say your BIOS needs an update or some tweakings.
The (usable) parts that it gives to the OS (linux) are :
0000000000000000 - 000000000009fc00
0000000000100000 - 0000000037fd0000
Thats not 1024 MB, but 892 MB
Here is the output on a 16 GB x86_64 machine
BIOS-provided physical RAM map:
BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved)
BIOS-e820: 0000000000100000 - 000000007fff0000 (usable)
BIOS-e820: 000000007fff0000 - 000000007ffff000 (ACPI data)
BIOS-e820: 000000007ffff000 - 0000000080000000 (ACPI NVS)
BIOS-e820: 00000000ff780000 - 0000000100000000 (reserved)
BIOS-e820: 0000000100000000 - 0000000480000000 (usable)
On node 0 totalpages: 2097039
On node 1 totalpages: 2097152
total of 4194078 pages (while exact 16GB should be 4194304 pages)
next prev parent reply other threads:[~2007-06-02 8:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-02 4:51 Missing RAM on x86_64 Mike Richards
2007-06-02 8:51 ` Eric Dumazet [this message]
2007-06-04 19:13 ` Lennart Sorensen
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