Re: [dmidecode] dmidecode 3.2 shows strange memory Total Width

[Jean Delvare]

Hi Alex,

On Wed, 2019-11-06 at 15:07 +0100, Axel Rau wrote:
> I have a new install of Ryzen 7 3700X on a Asrock X470D4U motherboard.
> The OS is FreeBSD 12.1.
> I try to find out, if ECC enabled.
> 
> On a Xeon E5 CPU, dmidecode shows Total Width: 72 bits und Data Width: 64 
> bits.
> 72-64=8; These are the 8 parity bits.

Sounds right.

> The Ryzen CPU shows Total Width von 128 Bit und Data Width: 64 bits.
> 
> Is this a bug in the Bios or in demidecode or is ECC not enabled?

I've seen this only once before, definitely looks like a BIOS bug. ECC
is typically +8 bits for 64-bit wide modules. You may want to check if
a BIOS update is available for your system, and if not (or if it
doesn't solve the problem), report to the manufacturer.

> PS: I get:
> root@b5:~ # dmidecode  -t memory
> # dmidecode 3.2
> # SMBIOS entry point at 0xed2b3000
> Found SMBIOS entry point in EFI, reading table from /dev/mem.
> SMBIOS 3.2 present.
> 
> Handle 0x000F, DMI type 16, 23 bytes
> Physical Memory Array
>     Location: System Board Or Motherboard
>     Use: System Memory
>     Error Correction Type: Multi-bit ECC

This says ECC is enabled.

>     Maximum Capacity: 128 GB
>     Error Information Handle: 0x000E
>     Number Of Devices: 4
> 
> Handle 0x0017, DMI type 17, 84 bytes
> Memory Device
>     Array Handle: 0x000F
>     Error Information Handle: 0x0016
>     Total Width: 128 bits
>     Data Width: 64 bits
>     Size: 16384 MB
>     Form Factor: DIMM
>     Set: None
>     Locator: DIMM 0
>     Bank Locator: P0 CHANNEL A
>     Type: DDR4
>     Type Detail: Synchronous Unbuffered (Unregistered)
>     Speed: 2666 MT/s
>     Manufacturer: Kingston
>     Serial Number: E72F267D
>     Asset Tag: Not Specified
>     Part Number: 9965745-002.A00G

Definitely a reference of ECC memory. decode-dimms should say that too.
I think your best option is to enter the BIOS setup screen and check
the memory configuration there, maybe there's a configuration option to
enable/disable ECC, or at the very least it should tell you whether ECC
is enabled or not.

>     Rank: 2
>     Configured Memory Speed: 2400 MT/s
>     Minimum Voltage: 1.2 V
>     Maximum Voltage: 1.2 V
>     Configured Voltage: 1.2 V
>     Memory Technology: DRAM
>     Memory Operating Mode Capability: Volatile memory
>     Firmware Version: Unknown
>     Module Manufacturer ID: Bank 2, Hex 0x98
>     Module Product ID: Unknown
>     Memory Subsystem Controller Manufacturer ID: Unknown
>     Memory Subsystem Controller Product ID: Unknown
>     Non-Volatile Size: None
>     Volatile Size: 16 kB
>     Cache Size: None
>     Logical Size: None

As a side note, I am collecting SMBIOS 3.2 implementations for my
dmidecode test suite, so I would appreciate if you could run "dmidecode
--dump-bin" on your system and send me the generated file (privately).
Thanks!

-- 
Jean Delvare
SUSE L3 Support