PCIe Hot Plug support standardization challenges in ATCA

TL;DR

This paper discusses the challenges and proposes solutions for standardizing PCIe Hot Plug support in ATCA systems, focusing on hardware implementation and event management to enhance high availability features.

Contribution

It introduces an extension for Hot Plug support on ATCA Hub Boards and addresses standardization issues for PCIe Hot Plug in ATCA.

Findings

Extended Hot Plug support for ATCA Hub Boards implemented.

Identified key issues for PCIe Hot Plug standardization in ATCA.

Stimulated discussion within PICMG community for standard development.

Abstract

Throughout the last decade, the Advanced Telecommunications Computing Architecture (ATCA) solidified its position as one of the main switched-based crate standards for advanced Physics instrumentation, offering not only highly performant characteristics in data throughput, channel density or power supply/dissipation capabilities, but also special features for high availability (HA), required for latest and upcoming large-scale endeavours, as is the case of ITER. Hot Swap is one of the main HA features in ATCA, allowing for Boards to be replaced in a crate (Shelf), without powering off the whole system. Platforms using the Peripheral Component Interconnect Express (PCIe) protocol on the Fabric Interface must be complemented, at the software level, with the PCIe Hot Plug native feature, currently not specified for the ATCA form-factor. From a customised Hot Plug support implementation for ATCA Node Boards, the paper presents an implementation extension for Hub Boards, allowing Hot Plug of PCIe switching devices, without causing bus enumeration problems. This paper further addresses the main issues concerning an eventual standardization of PCIe Hot Plug support in ATCA, such as the implementability of Hot Plug Elements and the generation and management of Hot Plug Events, aiming to stimulate the discussion within the PICMG community towards a long overdue standardized solution for Hot Plug in ATCA.