PCIE SPEC 4.0（PCI-SIG ENGINEERING CHANGE NOTICE）

ePTM is an improvement on the existing Precision Time Measurement capability that

provides improved detection and handling of error cases. ePTM quickly identifies and

resolves errors that may cause clocks to become desynchronized.

A design implementing ePTM will benefit from improved detection and handling of error

cases that would otherwise cause clocks to become desynchronized.

ePTM uses the same software interface as PTM. Existing PTM software should be

compatible with new ePTM implementations. No software changes should be necessary

to enable ePTM.

The only change visible to software is the addition of the ePTM Capable bit to the PTM

Extended Capability.

This ECN allocates previously reserved bits and requires the creation of new tests for the

new register fields. ePTM Asserts additional operational requirements on PTM

Requesters and PTM Responders. These additional requirements are a superset of the

existing PTM requirements. New C & I tests would be required if it is desirable to extend