introduction.adoc

Introduction

This specification provides the processor-specific application binary interface document for RISC-V.

This specification consists of the following three parts:

• Calling convention

• ELF specification

• DWARF specification

A future revision of this ABI will include a canonical set of mappings for memory model synchronization primitives.

Terms and Abbreviations

This specification uses the following terms and abbreviations:

Term	Meaning
ABI	Application Binary Interface
gABI	Generic System V Application Binary Interface
ELF	Executable and Linking Format
psABI	Processor-Specific ABI
DWARF	Debugging With Arbitrary Record Formats
GOT	Global Offset Table
PLT	Procedure Linkage Table
PC	Program Counter
TLS	Thread-Local Storage
NTBS	Null-Terminated Byte String
XLEN	The width of an integer register in bits
FLEN	The width of a floating-point register in bits
PTRSZ	The width of a pointer type in bits (8*sizeof(void *))
Linker relaxation	A mechanism for optimizing programs at link-time, see [Linker Relaxation] for more detail.
RVWMO	RISC-V Weak Memory Order, as defined in the RISC-V specification.

Status of ABI

ABI Name	Status
ILP32	Ratified
ILP32F	Ratified
ILP32D	Ratified
ILP32E	Draft
LP64	Ratified
LP64F	Ratified
LP64D	Ratified
LP64Q	Ratified
RV64ILP32	Draft
RV64ILP32F	Draft
RV64ILP32D	Draft
RV64ILP32Q	Draft

Note	ABI for big-endian is NOT included in this specification, we intend to define that in future version of this specification.

Any encodings that are marked as reserved for a specific extension (ISA or purely ABI addition) should be treated by standard tools identically to any other encodings reserved for future standard extensions. Such reservations are solely declarations of intent to reduce conflicts between in-flight standard extensions, and may be reclaimed for future reassignment at any point for any reason. Any encodings marked as reserved have draft, not ratified, status, regardless of whether they are reserved for a ratified ISA extension.