Question regarding UUID and SMBIOS

adrianfreemantle · ‎08-06-2007

Hi there,

This question is more out of curiosity and to help anyone else who may encounter this in the future.

I recently compared the UUID returned by AMT against the SMBIOS system GUID as i was convinced that this is where AMT was obtaining the UUID from and we want to use this information for automated provisioning. I noticed that the SMBIOS and AMT UUID are not exactly the same, it seems as though the AMT version has had some of the data swapped into network byte order, see below:

ORIGINAL GUID FROM SMBIOS
D091BBDE-3825-11DB-8F15-000EA68F75B9

ORDER FOR AMT UUID
DEBB91D0-2538-DB11-8F15-000EA68F75B9

Now although it is easy to adjust the two to match each other, I was curious as to why AMT would change this information. I looked at the GUID reported by a few tools, including PXE and all used the same format, only AMT and WMI change the byte order.

Now just out of curiosity i would like to ask; does any one know why this information is reported this way?

john_prothro · ‎08-06-2007

MicroSoft refers to the difference as "pretty print" vs. "raw byte order"...

the following url describes it... look for the phrases above to see their description.

http://www.microsoft.com/technet/prodtechnol/windows2000serv/reskit/distrib/dsed_dpl_rutr.mspx?mfr=true

I hope this helps some... however, I don't really know why it is done...

john_prothro · ‎08-09-2007

I have noticed that my code relating to the power package guid's has the following comment in it...

// the real guid in non human consumable...CDE 1.1 RPC specification

I could not remember exactly why I put that in there, so I looked around and thought this might be of some interest to someone who was curious as I was when I first encountered the guid byte order. Here is the link to the uuid spec from the code comment above...

http://www.opengroup.org/onlinepubs/9629399/apdxa.htm#tagcjh_20