With the ever-increasing complexity of the PCI Express® Gen5/6 and CXL™ protocols, integrating next-generation IP into your design quickly and securely can be a daunting task. We spoke with Julien Eydoux, the leader of the XpressAGENT development team, to find out how Rambus’ new chip-level add-on module solution can help customers rise to this challenge.
“We developed XpressAGENT in response to our observations in the field; our customers were spending time and money adding their own logic and functions to integrate their PCIe or CXL IP into their design and to test that integration. This proved to be a costly and often error-prone practice, and meant our customers sometimes failed to benefit from the full breadth of our IP cores’ functionalities.”
With the creation of XpressAGENT, the aim was to save customers time and money, by providing a complete solution to:
- Integrate their Rambus IP into their design as rapidly and smoothly as possible
- Accelerate silicon bring-up using a trustworthy and comprehensive debug & monitoring solution
- Benefit from extra RAS features, such as error injection and remote monitoring, in addition to those defined in the PCIe and CXL specifications
Let’s look at how XpressAGENT meets our customers’ needs
“XpressAGENT integrates with any Rambus IP Core to enable customers to observe and manage signals from either their PCIe or CXL subsystem. It allows easy control, monitoring, testing, and debug of the subsystem. Multiple register access ports are coalesced to simplify RTL integration, ease verification and expedite device silicon bring-up. It also provides a logic analyzer feature that enhances observability, and additional aids for monitoring states and events such as counters, interrupts, and status registers.
We offer XpressAGENT with each of our Rambus PCIe and CXL controllers, thereby simplifying the integration process for our customers. Furthermore, the controller can now itself be configured directly via XpressAGENT.
We can also use XpressAGENT to configure the PCIe/CXL PHY – from Rambus or any third-party. Customers can then monitor the PIPE interface between the Controller and the PHY to examine and verify communication between the two.
In addition, XpressAGENT enables users to configure their subsystem via software instead of hardware, which reduces risk and adds flexibility to the design process. The software API we provide can be used to rapidly create the software required to manage the IP Controller and incorporate it into the customer’s system hardware, again saving integration and validation time and effort.
The software API can also be used connect to the chip through a remote computer to monitor and debug the system. So, the API can be used internally in the circuit or remotely.”
With the rapid evolution of PCI Express and the development of the CXL protocol, debugging and monitoring information is crucial to enable customers to quickly identify and debug any problems that occur.
“Data rates are now so fast that it’s very complicated to use standard external solutions to analyze low-level details. Additionally, costs for debugging are rapidly increasing and can get very complicated to manage. With XpressAGENT, customers have a comprehensive range of debugging tools at their disposal, so they have clearer information if problems arise, and they save time because the logic to implement these tools is already provided.”
An important feature of the latest PCI Express Specs is RAS (Reliability, Accessibility, Serviceability).
“Being able to add debug information and inject errors into a system to see how it behaves enables us to analyze the system’s robustness and observability from a PCIe perspective.
Our IP solutions implement all the RAS features required by the PCIe Spec, but XpressAGENT also adds an extra level of information beyond the spec. For example, XpressAGENT adds specific I/0s to the Controller to force and inject errors into the system. Injecting errors from outside can be done easily with XpressAGENT, but if you don’t have that, it’s hard to control and inject errors.”
The Logic Analyzer built in to XpressAGENT enables customers to record communication between the PHY and the Controller, or within the Controller itself.
“The analyzer allows us to remotely record all the PHY and Controller information triggered by a user defined event, allowing us to record the activity of all internal signals to examine signal and state transitions occurring within a specific time window.
Despite the deluge of data at high bandwidths in the order of terabits per second, recording link operation in a certain fixed time window is critical to understanding what is going on, to debug if necessary, and to verify that everything is functioning as expected. It helps to speed up silicon bring-up. When our customers have their chips fab’ed and receive them in their labs, they can start testing the chips straight away.”
One of the major benefits of XpressAGENT is that it can be used for remote access in the field.
“Say one of our customers fabricates a chip based on our IP and then delivers that chip to one of their clients. If a problem occurs in the client’s system, they can use the software created with XpressAGENT to connect to the client site, identify and root cause the anomaly. They can then use XpressAGENT to analyze and debug in real time, avoiding having to shut down systems or recall their product.”
You can find more information about XpressAGENT here.