Keeping Time with Intel® AMT

By Lance Atencio (Intel) (21 posts) on February 25, 2010 at 3:46 pm

The date/time used by Intel® Active Management Technology (AMT) is maintained by a protected real time clock (PRTC) running within the Manageability Engine.

Clock Usage

The clock is used for a variety of reasons in AMT including date/time checks required for TLS and Kerberos usage, timestamps for events and logging, and maintaining alarms for the Alarm Clock feature.

Setting the Clock

The clock can be set in a few ways, dependent on how AMT was provisioned.

Set manually (locally) through the Manageability Engine BIOS Extensions (MEBx) via “Intel® AMT Configuration > Set PRTC”
Synchronize to a server’s time remotely through the API. The WS-Management class AMT_TimeSynchronizationService does this with the two calls GetLowAccuracyTimeSynch and SetHighAccuracyTimeSynch. The clock has to be set remotely during Enterprise mode configuration on systems prior to AMT 6.0 or the configuration will not succeed.
The clock will automatically be synchronized at boot time with the local BIOS clock for systems configured in Small Business (SMB) mode (systems prior to AMT 6.0).

New in AMT 6

In AMT 6.0 there is no longer an SMB mode. Check out What's new with Provisioning and Intel(r) AMT 6.0. When an AMT 6.0 system is configured manually the clock will be synchronized to the BIOS clock at boot time.

For Enterprise mode in AMT 6.0, as long as TLS/Kerberos are not enabled, the clock does not need to be remotely configured in order to complete provisioning. If Enterprise mode provisioning is completed without remotely setting the clock, then the clock will be synchronized to the BIOS clock.

In the Zone

The clock used by AMT does not maintain knowledge of time zone. So it would be a good idea to maintain knowledge of how the clock has been/is being set and what the local time is for that system. This is important when setting the Alarm Clock or reading timestamps in the usages mentioned above.

If the clock is being synchronized with the BIOS clock you should keep in mind that Microsoft Windows will typically set the BIOS to the local time being kept by the operating system (see The Old New Thing). I believe Unix/Linux systems normally set the BIOS clock to Coordinated Universal Time (UTC).