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jbennett0
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after adding 16G compatible memory, I find 8 GB missing server memory with acpi bios: dmidecode sees 32G, free sees 24

I recently added 16G of Hynix memory (HYMP151F72CP4N3-Y5) to a Dell t7400 workstation that contained 16G
of memory as originally shipped (M395T5166AZ4-CE65).

dmidecode -t 17 | grep Size | grep MB
Size: 4096 MB
Size: 4096 MB
Size: 4096 MB
Size: 4096 MB
Size: 4096 MB
Size: 4096 MB
Size: 4096 MB
Size: 4096 MB
Also, the Dell mboard ACPI bios sees all 32G. Memtest passes on all 8 memory modules of 4mb
each. (So reordering or reseating the memory modules won't solve this. I
tried this already.)
I'm using the last bios posted to Dell's support pages:
>dmidecode -s bios-version
A0
>dmidecode -s bios-release-date
05/23/20119

After I boot into linux, the system sees only 24G.

dmesg:

[ 0.000000] e820: BIOS-provided physical RAM map:
[ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009c3ff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x00000000cfe0abff] usable
[ 0.000000] BIOS-e820: [mem 0x00000000cfe0ac00-0x00000000cfe5cbff] ACPI NVS
[ 0.000000] BIOS-e820: [mem 0x00000000cfe5cc00-0x00000000cfe5ebff] ACPI data
[ 0.000000] BIOS-e820: [mem 0x00000000cfe5ec00-0x00000000cfffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000e0000000-0x00000000efffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fe000000-0x00000000feffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000ffb00000-0x00000000ffffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000062fffffff] usable

which is only 26575110143 bytes!

>free -m
total used free shared buffers cached
Mem: 24109 6941 17167 38 577 4225

>grep line /sys/devices/system/memory/*/state -> all online
But memory26-29 are not detected: total lines = 192. Why? 192x8M -> 24G
only. But 4x8M -> 32M, not enough to account for the missing ram. Are
memory26-29 reserved?


>dmesg | grep eserved
[ 0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000cfe5ec00-0x00000000cfffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000e0000000-0x00000000efffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fe000000-0x00000000feffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000ffb00000-0x00000000ffffffff] reserved
[ 0.000000] e820: update [mem 0x00000000-0x00000fff] usable ==> reserved
[ 0.000000] e820: update [mem 0xcff00000-0xffffffff] usable ==> reserved
[ 0.000000] DMA zone: 21 pages reserved
[ 0.000000] Memory: 24672120K/25163412K available (6571K kernel code, 1086K
rwdata, 4856K rodata, 1560K init, 1520K bss, 491292K reserved, 0K
cma-reserved)

Looks like the reserved memory is not nearly enough to account for the
discrepancy.

MTRR?
>dmesg | grep MTRR
[ 0.000000] MTRR default type: uncachable
[ 0.000000] MTRR fixed ranges enabled:
[ 0.000000] MTRR variable ranges enabled:
dmesg gives no warnings.

This machine also runs an ancient copy of Windows Vista Business. That
produces the same pattern: the Dell  bios sees all 32G but the OS only 24.

Adding the boot parameter mem=32G has no effect (because, by the point that
the boot process loads the kernel, the visible memory is already reduced).

So apparently something happened when the bios created the physical ram map.
Which causes the loss of 8G?

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7 Replies
Community Manager
Community Manager

RE: after adding 16G compatible memory, I find 8 GB missing server memory with acpi bios: dmidecode sees 32G, free sees 24

The maximum RAM compatibility for Windows Vista Business is only 4GB.  http://dell.to/2efbU7A

Perhaps a different OS will utilize the remainder.


Dell-Robert P
Social Media Support
#IWork4Dell
To help us troubleshoot, please send us the Dell service tag number via a private message
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jbennett0
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RE: after adding 16G compatible memory, I find 8 GB missing server memory with acpi bios: dmidecode sees 32G, free sees 24

This machine has run 64-bit vista on 16gb since 2011.

The os that I use is

> uname -a

Linux linux-2v1c 4.1.34-33-default #1 SMP PREEMPT Thu Oct 20 08:03:29 UTC 2016 (fe18aba) x86_64 x86_64 x86_64 GNU/Linux

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Community Manager
Community Manager

RE: after adding 16G compatible memory, I find 8 GB missing server memory with acpi bios: dmidecode sees 32G, free sees 24

Since this forum is primarily consumer oriented, your post might be answered better in the Dell Tech Center Forum where there are server experts available.


Dell-Robert P
Social Media Support
#IWork4Dell
To help us troubleshoot, please send us the Dell service tag number via a private message
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jbennett0
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RE: after adding 16G compatible memory, I find 8 GB missing server memory with acpi bios: dmidecode sees 32G, free sees 24

Can you offer a more specific url?  From the link you provide I find nothing relelvant (except "extras" with no contribution

since 2014)

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Community Manager
Community Manager

RE: after adding 16G compatible memory, I find 8 GB missing server memory with acpi bios: dmidecode sees 32G, free sees 24

Try this link:  https://community.emc.com/welcome?dgc=IR&cid=304513&lid=5776114

Or this link: http://en.community.dell.com/techcenter/os-applications/f

Or this link: http://en.community.dell.com/techcenter/f/


Dell-Robert P
Social Media Support
#IWork4Dell
To help us troubleshoot, please send us the Dell service tag number via a private message
Would you like to be a Dell Community Rockstar?


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jbennett0
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RE: after adding 16G compatible memory, I find 8 GB missing server memory with acpi bios: dmidecode sees 32G, free sees 24

I don't follow what you are trying to do.

1st link: general intro page

2nd link: forum, which I already searched

3rd link: another forum, which I joined, which lacks content and doesn't accept questions.

I gather you have no clue.

It has been suggested by two persons on the suse forum that the dell bios is broken.  Maybe so.  But why is 24G seen by the OS?

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Community Manager
Community Manager

RE: after adding 16G compatible memory, I find 8 GB missing server memory with acpi bios: dmidecode sees 32G, free sees 24

Since this Forum is primarily consumer products, I was attempting to give you more resources so you can ask your questions to those experts who deal with servers.  

Here is another forum where you can post your question, which is more similar to this one and has some excellent experts working there:

http://dell.to/2en0b6W




Dell-Robert P
Social Media Support
#IWork4Dell
To help us troubleshoot, please send us the Dell service tag number via a private message
Would you like to be a Dell Community Rockstar?


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