How to get the SPD infomation in freebsd ?

C. P. Ghost cpghost at
Tue Jun 29 16:00:49 UTC 2010

On Tue, Jun 29, 2010 at 7:51 AM, Matthew Seaman
<m.seaman at> wrote:
> On 29/06/2010 03:29:04, zaxis wrote:
>> In windows, the `CPU-Z` utility can be used to get the SPD(Serial Presence
>> Detect) information. How about freebsd ? I want to get those information
>> especially frequency to add more memory. And i donot want to touch the
>> hardware.
> Try dmidecode(8) -- it's in ports.  This will tell you quite a bit of
> information about what type of RAM you have installed, but it may be
> more productive to look up the Motherboard model numbers it returns, and
> find compatible RAM that way.

dmidecode(8) is better than nothing, but it doesn't return SPD data for me:

Handle 0x002B, DMI type 17, 27 bytes
Memory Device
        Array Handle: 0x0029
        Error Information Handle: Not Provided
        Total Width: 64 bits
        Data Width: 72 bits
        Size: 2048 MB
        Form Factor: DIMM
        Set: None
        Locator: DIMM0
        Bank Locator: BANK0
        Type: DDR2
        Type Detail: Synchronous
        Speed: 400 MHz
        Manufacturer: Manufacturer0
        Serial Number: SerNum0
        Asset Tag: AssetTagNum0
        Part Number: PartNum0

(Maybe those DIMMS aren't SPD capable? I don't know).

According to
dmidecode(8) reads only BIOS data, but not the eeprom from
the DRAM modules themselves. The same page also points
to spdmem(4).

OpenBSD's spdmem(4) driver could be interesting to port to FreeBSD:
as it allegedly reads the eeprom data directly off the DIMM modules.

> Even so, for best results it helps if you install a uniform set of RAM
> modules, and I don't think there's any option other than popping the
> case and pulling a RAM stick for a visual inspection if you want a 100%
> certain match.

I've already seen mislabled DIMMS in the past, and usually, the
information stored in SPD was more reliable than the one on the
stickers (but not always).

>        Cheers,
>        Matthew


Cordula's Web.

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