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This page gives an overview of the extension and feature support in the RISC-V SW ecosystem.

Overview

Table description

The subsections below contain tables that summarize the current state of extensions and features. The following description helps to interpret the table cell's contents:

  • upstream...SW support has been merged into the main development branch of the corresponding SW project
  • staging branch...SW support lives in a staging branch and is not upstreamed
  • PR...SW support exists in form of a pull request for upstream (in-review or waiting for ratification)
  • n/a...not applicable, not relevant, or not required
  • missing...currently no known implementation
  • dev:X...feature is in development by X
  • empty cells...unknown status (feel free to share your knowledge)

ISA extension naming conventions

This is just a summary of the naming convention as defined in the unpriv specification.

ISA extension description example: RV64I1p0M1p0A1p0F1p0D1p0 or RV32I2_M2_A2 (P extension requires underscore!)

Prefixes:

  • Extensions with prefix Z...standard user-level
  • Extensions with prefix X...non-standard user-level
  • Extensions with prefix S...standard supervisor-level
  • Extensions with prefix SX...non-standard supervisor-level

Published specifications (20191213)

The table below lists the status of the extensions and features of above listed published extensions.

ExtensionSpikeQemuBinutilsGCCglibcnewlibLLVMOpenSBIFreeBSDLinux kernel

GDB

RV32Iupstreamupstreamupstreamupstreamupstreamupstreamupstreamupstreamnot supportedupstreamupstream
RV64Iupstreamupstreamupstreamupstreamupstreamupstreamupstreamupstreamupstreamupstreamupstream
Big-endian supportupstream

upstream

not supported
not supported
upstream
M (Multiplication and Division)upstreamupstreamupstreamupstreamn/an/aupstreamn/an/an/aupstream
A (Atomic)upstreamupstreamupstreamupstreamn/an/aupstreamupstream (atomics)upstream (atomics)upstream (atomics)upstream
F (SP float)upstreamupstreamupstreamupstreamupstreamupstreamupstream
upstreamupstreamupstream
D (DP float)upstreamupstreamupstreamupstreamupstreamupstreamupstream
upstreamupstreamupstream
Q (QP float)

upstream


not supported
not supported
upstream
RVWMOupstream (emulation is seq. consistent)upstream (emulation is seq. consistent)n/an/an/an/an/aupstream (barriers and locks)upstream (barriers and locks)upstream (barriers and locks), but needs optimizationupstream
C (compressed)upstreamupstreamupstreamupstreamn/an/aupstream
upstreamupstream
Zifenceiupstreamupstreamupstreamupstream

not supported
upstreamupstream
Machine ISA: CSRsupstreamupstreamupstream




n/a

Machine ISA: ECALL, EBREAKupstreamupstream





upstreamupstream
Machine ISA: MRET/SRET/URETupstreamupstream





n/a

Machine ISA: WFIupstreamupstream





upstreamupstream
Machine ISA: PMP







n/a

Supervisor ISA: CSRsupstreamupstream





upstream

Supervisor ISA: SFENCE.VMAupstreamupstream





upstreamupstream
Supervisor ISA: Sv32, Sv39, Sv48upstreamupstream





Sv39 upstreamupstream (sv39)

Unpublished ratified extensions

Extensions and features in the table below are ratified, but not published in a consolidated RISC-V ISA specification document.

ExtensionSpikeQemuBinutilsGCCglibcnewlibLLVMOpenSBIFreeBSDLinux kernel

GDB

ZihintpauseupstreamMailpatchupstream


upstream



Vector: Zvamo, Zvlsseg, Zvediv, Zvqmac, Zve32x, Zve32f, Zve64x, Zve64f, Zve64d, Zvfh, Zveupstream

upstream

upstreamrvv-next branch

upstreamupstream (experimental,FP16 ABI not settled)not supported

Bitmanip: Zba, Zbb, Zbc, Zbsupstreamupstream

upstream

PRdev branch
upstreamupstream (experimental)not used

FP in INT regs: ZfinxPR
upstreamupstream(Zfinx, Zdinx)


Mailpatch

(Zfinx,Zdinx)




MC upstream
not supported

Half Width FP: Zfh, Zfhminupstreamupstreamupstream (Zfh only)
Mailpatch (Zfhmin)



upstream
not supported

ePMP: Smepmpupstreamupstream(but 0.9.3)upstream (CSR only; part of Priv 1.12 support)


PR
not supported

Scalar crypto: Zbkb, Zbkc, Zbkx, Zknd, Zkne, Zknh, Zksed, Zksh, Zkn, Zks, Zkt, Zk, Zkrupstreamupstreamupstreamupstream(only minimal support and wait c-api merge)



upstream


not used

Priv 1.12: 
Sm1-12, Ss1-12, Sv57

upstreamupstream




not supported

CMO base: Zicbom, Zicbop, ZicbozupstreamMailpatchupstream


PR,PR
not supported

Hypervisor: Hupstreamupstreamupstream (except handling as 'H' extension; now a part of 'I' extension)n/an/an/a
upstreamnot supportedupstream (5.16)
State Enable: Smstateen
MailpatchMailpatch




not supported

Time compare: Sstc
MailpatchMailpatch




not supported

Counter overflow and filtering: Sscofmpf
MailpatchMailpatch




not supported

Fast TLP invalidation: Svinvalupstreamupstreamupstream




not supported

NAPOT pages: Svnapotupstreamupstream





not supported

Page-based memory types: Svpbmtupstreamupstream





not supported

Code Size Reduction: Zceedev branchdev branchdev branchdev branch

dev branch
not supported

Packed SIMD:  Zpn, Zpsfoperand, Zprvsfextraupstream(

v0.9.2)

MailpatchPRPR



not supported

Resumable Non-maskable Interrupts: Smrnmi







not supported

Core-local Interrupt Controller: CLINTupstreamupstream





upstreamupstream (clocksource)
Advanced Core-local Interrupt Controller: ACLINT
upstream





not supportedPatchwork
ZmmulupstreamMailpatchMailpatchMailpatch

patch
n/a

Pointer masking: Zjpm







not supported

Specifications that are at least frozen

Extensions and features in the table below are either frozen or ready-for-ratification.

ExtensionSpikeQemuBinutilsGCCglibcnewlibLLVMOpenSBIFreeBSDLinux kernel

GDB

-none-










Specifications that are at least stable

Note, that this section only lists specifications that are planned to be released in the near future, but are not frozen yet.

ExtensionSpikeQemuBinutilsGCCglibcnewlibLLVMOpenSBIFreeBSDLinux kernel

GDB

psABI: Standard ABIs: ILP32, ILP32F, ILP32D, LP64, LP64F, LP64D, LP64Qn/an/aupstreamilp32, ilp32f, ilp32d, lp64, lp64f, lp64dilp32, ilp32d, lp64, lp64dilp32, ilp32f, ilp32d, lp64, lp64f, lp64dilp32, ilp32d, lp64, lp64dn/alp64, lp64dn/a

Specifications that are not stable

Note that this section only exists for historical purposes and the table below is not considered complete. Further, there are no attempts to track the SW support of unstable features here. 

ExtensionSpikeQemuBinutilsGCCglibcnewlibLLVMOpenSBIFreeBSDLinux kernel

GDB

Embedded ABI: ILP32E, LP64En/an/aupstreamupstreamnot supportedupstreamnot supportedn/an/an/anot supported

Gaps

  • Vector Extension Intrinsics (specification exists, but not frozen)
  • Vector Calling Convention (specification exists, but not frozen)
  • Scalar Crypto Intrinsics
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