RISC-V FDPIC - NOMMU Toolchain - Runtime Support

Explore the intricacies of RISC-V FDPIC/NOMMU toolchain and runtime support in this 27-minute conference talk from linux.conf.au 2020. Delve into the challenges of implementing PC-relative addressing in NOMMU systems and the proposed solution using function descriptors and GP-relative addressing. Learn about the FDPIC psABI design for RISC-V systems, including modified function calling conventions and new data structures. Gain insights into the required toolchain and runtime changes for Linux/GNU systems. Cover topics such as shared program mapping, GP-relative addressing, procedure calls, lazy binding, and implementation goals for RISC-V FDPIC support.

Intro
Western Digital
Overview
Design Goals and Non-Goals
MMU PIC Shared Program Mapping
NOMMU PIC (Flat) Unshared Program Mapping
NOMMU FDPIC Shared Program Mapping
Text To Data Addressing
GP-Relative Addressing
Local Data Addressing
External (Preemptible) Data Addressing Using the Global Offset Table (GOT)
Procedure Calls
FDT Structure Dynamic relocation required
Taking A Function's Address
Lazy Binding
Implementation Goals