Raptor Computing Systems Community Forums (BETA)

Raptor Computing Systems Hardware => Talos II => Topic started by: pocock on June 01, 2020, 02:05:08 am

Title: OCuLink ambiguity
Post by: pocock on June 01, 2020, 02:05:08 am

When I look at the ordering pages on the Raptor site, it offers various OCuLink products:

The manual:

includes errata stating that

╬╝PCIe connector (J10108) is incorrectly identified as OCuLink (SFF-8621) due to errors that were discovered post-production in IBM OpenPOWER reference designs.  While the physical connector is the same as OCuLink ports, the wiring is different, notably in the presence detect / clocking pins.  As such, while an OCuLink peripheral is unlikely to be damaged by being plugged in to the ╬╝PCIe port, it will not function while attached.

If that is the case, buyers selecting the OCuLink products will not be able to use them - or has the board design been changed somehow to make OCuLink work?
Title: Re: OCuLink ambiguity
Post by: pocock on June 17, 2020, 06:02:02 am

From the Thunderbolt 3 thread (https://forums.raptorcs.com/index.php/topic,105.0.html)...

The only thing I can say is that a working OCuLink adapter (https://wiki.raptorcs.com/wiki/POWER9_Hardware_Compatibility_List/PCIe_Devices#Working_4) is listed in the RCSwiki.

but it is odd that the ordering page includes an option to select an OCuLink PCIe Expander but the form doesn't include any of the OCuLink adapters.  When I noticed that, it left me wondering if there is OCuLink support on the motherboard.  It would be no use for somebody to order the expander and motherboard without also ordering one of the OCuLink adapter cards.