Link training through handshake on high-speed interconnect

A first device comprising:

• training logic;
• a serializer/deserializer coupled to the training logic, wherein the training logic is to:
• train a ground-referenced signaling (GRS) link in a first direction between the first device and a second device;
• and
• send or receive a first sideband message on the GRS link in a second direction between the second device and the first device.

A system comprising:

• a first device;
• a second device;
• and
• a ground-referenced signaling (GRS) link coupled between the first device and the second device, wherein the first device comprises:
• a training logic;
• a serializer/deserializer coupled to the training logic, wherein the training logic is to:
• train the GRS link in a first direction between the first device and a second device;
• and
• send or receive a first sideband message on the GRS link in a second direction between the second device and the first device.