RISC-V
Instruction Set Architecture

General

• History
• Families

Base Variants(base)

• RV32
• RV64
• RV128

Standard Extensions(all)

• A
• B
• C
• D
• E
• F
• G
• I
• J
• L
• M
• N
• P
• Q
• T
• V

Topics

• Foundation
• Non-Standard Extensions
• Addressing Modes
• Registers
• Assembly
• Interrupts
• Microarchitectures

Because RISC-V is designed to provide the foundation for more specialized hardware, RISC-V offers the ability to extend the architecture with non-standard extensions which refers to additional instructions offered by third parties that are not part of RISC-V officially recognized standard extensions.

Overview

In addition to the RISC-V standard extensions, the ISA allows for custom third party ISA. The intention of custom extensions is to allow designers to implement additional highly specialized instructions.

• Xabc - Non-standard User-level extension "abc"
• SXabc - Non-standard Supervisorlevel extension "abc"

For example RV32IXabc.

Non-standard extensions

This list is incomplete; you can help by expanding it.