Go

Author: Ludovic HENRY ludovic.henry@qti.qualcomm.com
Date: 2026-06-17
Scope: RISC-V (riscv64/linux) support status for Go
Audience: Technical leadership, resource allocation strategy
Verification policy: Every claim is cross-referenced to a primary upstream source. Items that could not be verified against a second source are marked [NEEDS VERIFICATION].

1. Project Overview

Go is a compiled, garbage-collected systems programming language developed and maintained by Google. It is not affiliated with any independent foundation (no CNCF, Linux Foundation, or similar body). The project is governed by a small core team of Google employees. Final merge authority rests with the Google core team; the contribution process requires +2 Code-Review approval from a Go maintainer. Significant language or runtime changes require a formal accepted proposal. Go is not a RISE Project member. RISE Premier Members include Google, Red Hat, NVIDIA, SiFive, Qualcomm, MediaTek, Andes Tech, Tenstorrent, and DAMO Academy (Alibaba).

2. Port History and Upstreaming Timeline

The linux/riscv64 port was a community-driven effort initiated by Tobias Klauser (Cilium/Isovalent) and completed primarily by Joel Sing (OpenBSD developer). An early out-of-tree port existed at github.com/riscv/riscv-go but was abandoned by 2018, which motivated the upstream effort.

Date Event Source
2018-04-11 First RISC-V commit: go/build, runtime/internal/sys: reserve RISC-V arch names (Tobias Klauser) commit 9446eaa9443c
2018-04-18 debug/elf: add riscv64 relocations (Tobias Klauser), references out-of-tree port commit 96f6cc15949c
2018-09-06 Issue #27532 “all: port to RISC-V” filed as official tracking issue issue #27532
2019-09-07 Joel Sing submits assembler and register definitions for cmd/internal/obj/riscv upstream Gerrit
2020-01-22 Joel Sing adds missing runtime code for linux/riscv64 upstream Gerrit
Feb 2020 Go 1.14: First official release with linux/riscv64, marked experimental Go 1.14 release notes
~2020 CGo support added for the riscv port, issue #36641 closed issue #36641
2024-01-25 openbsd/riscv64 port completed, issue #55999 closed issue #55999
2025-02-20 Plugin build mode (-buildmode=plugin) implemented for riscv64 (Gerrit CL 420114) commit cdc9560
2026 (current) Active development: vector ISA, compressed instructions, crypto, jump tables, atomic intrinsics tracker below

The port graduated from experimental status at some point after Go 1.14. The exact release that removed the experimental caveat is not recorded in the research findings. Data not available: precise Go version when linux/riscv64 was promoted from experimental to secondary port.

3. Upstream Support Tier

Go defines two port tiers.

First-class ports (broken builds block releases, Google-owned builders required): darwin/amd64, darwin/arm64, linux/386, linux/amd64, linux/arm, linux/arm64, windows/386, windows/amd64.

Secondary ports (broken builds do not block releases, community-maintained builders): linux/riscv64 is a secondary port. The consequences are:

  • A broken riscv64 build does not require a release rollback or delay.
  • The port requires at least two named maintainers listed in the golang/port-maintainers GitHub team subgroups.
  • Port-specific changes must be reviewed by a port maintainer before merge.
  • If a builder fails repeatedly with no fix in progress, the port may be removed in the next release.

The supported GOOS/GOARCH combinations for riscv64 are:

GOOS GOARCH CGo Status
linux riscv64 yes supported
freebsd riscv64 yes Broken (go.dev/issue/76475)
openbsd riscv64 yes supported

4. Technical Architecture and RISC-V-Specific Subsystems

The Go toolchain is self-hosted. RISC-V support spans the following subsystems.

4.1 Compiler Backend

  • src/cmd/compile/internal/riscv64/ssa.go (~650 lines): SSA code generation. Covers RV64I, M (mul/div), A (atomics LR/SC/AMO), F/D (float/FMA), Zba (SH1ADD/SH2ADD/SH3ADD), Zbb (CLZ/CTZ/CPOP/REV8/MIN/MAX/ANDN/ORN/XNOR), Zicond (CZEROEQZ/CZERONEZ).
  • src/cmd/compile/internal/ssa/rewriteRISCV64.go (11,227 lines, auto-generated): Full generic-to-RISC-V SSA translation. Zba/Zbb rules are gated on GORISCV64 >= 22.
  • src/cmd/compile/internal/ssa/rewriteRISCV64latelower.go (~330 lines, auto-generated): Late-lowering – fuses AND/OR/XOR+NOT into Zbb ANDN/ORN/XNOR; shift-extend elision.

4.2 Assembler Object Backend

  • src/cmd/internal/obj/riscv/cpu.go (~950 lines): All register constants (X0-X31, F0-F31, V0-V31), instruction mnemonics, relocation types, rounding modes, EncodeVectorType(). Covers RV64I, Zicsr, Zicond, M, Zalrsc, Zaamo, F/D/Q, C, Zba/Zbb/Zbc/Zbs, V, Zvbb/Zvbc, Privileged ISA.
  • src/cmd/internal/obj/riscv/inst.go (2,191 lines, auto-generated): encode() maps ~1,080+ instruction mnemonics to raw opcode tuples across 29 extension families.
  • src/cmd/internal/obj/riscv/obj.go (2,500+ lines): Full assembler pass including compressed instructions (CA/CB/CI/CIW/CJ/CL/CR/CS/CSS), vector config (Vsetvli/Vsetivli/Vsetvl), all R/I/S/B/U/J-type variants.

The compressed instruction (RVC) support was added in November 2025 via commits 9859b43 and b9ef063.

4.3 Linker

  • src/cmd/link/internal/riscv64/asm.go (~430 lines): ELF relocations, PLT/GOT, trampolines. Handles R_RISCV_CALL, R_RISCV_JAL, R_RISCV_PCREL_HI20/LO12, R_RISCV_GOT_HI20, R_RISCV_TLS_IE/LE, R_RISCV_RVC_BRANCH/JUMP, R_RISCV_ADD32/SUB32, R_RISCV_RELAX.

4.4 Runtime

  • src/runtime/asm_riscv64.s (~820 lines): Entry points, goroutine control, stack management, CGo interop, GC write barriers, reflection dispatch (27 CALLFN variants), cputicks via RDTIME.
  • src/internal/cpu/cpu_riscv64_linux.go (~97 lines): Runtime extension detection via riscv_hwprobe syscall (syscall 258). Detects: V, Zbb, Zbc, Zvbb, Zvbc, Zvkb, Zvkg, Zvkned, Zvknha/b, Zvksed, Zvksh, Zvkt, and fast-misaligned. Note: AT_HWCAP V-bit detection is used but documented as unreliable across vendors.
  • src/runtime/cgo/gcc_riscv64.S (~72 lines): crosscall1 – saves 14 integer + 12 float callee-saved registers for GCC-to-Go ABI bridge.

4.5 Standard Library – RISC-V-Specific Assembly

Package File ISA Extensions Notes
crypto/internal/fips140/sha256 sha256block_riscv64.s (~175 lines) Zbb (RORW) Scalar only – no Zvknha/b
crypto/internal/fips140/sha512 sha512block_riscv64.s (~215 lines) Zbb (ROR) Scalar only – no Zvknhb
crypto/internal/fips140/bigmod nat_riscv64.s (~90 lines) M (MUL/MULHU) addMulVVW{1024,1536,2048}
math dim_riscv64.s, exp_riscv64.s, floor_riscv64.s D, FMA FMAXD/FMIND, FMADDD/FNMSUBD
internal/bytealg indexbyte_riscv64.s RV64I Optimization open, PR #79997 pending
internal/bytealg memequal V (rva23u64) Vectorized, merged (commit 75ea2d05)
reflect float32reg_riscv64.s F, D NaN-box handling

4.6 ISA Extension Coverage Summary

Extension Assembler Compiler codegen Runtime detection Stdlib assembly
RV64I (base) Yes Yes N/A Yes
M (multiply) Yes Yes N/A Yes (bigmod)
A / Zalrsc / Zaamo (atomics) Yes Yes N/A –
F/D (float) Yes Yes N/A Yes (math)
C (compressed) Yes – N/A –
Zba Yes Yes (rva22u64+) – –
Zbb Yes Yes Yes Yes (sha256, sha512)
Zbc Yes – Yes –
Zbs Yes – – –
Zicond Yes Yes – –
Zicsr Yes – N/A –
V (RVV 1.0) Yes (full) – Yes Yes (bytealg)
Zvbb/Zvbc Yes (encoding) – Yes –
Zvkg/Zvkned/Zvknha/b/Zvksed/Zvksh/Zvkt Yes (encoding) – Yes –

5. Build System, Cross-Compilation, and Toolchain

Go uses its own make.bash / all.bash build system. There are no CMake files, no Dockerfiles, and no GitHub Actions workflow files in the repository.

5.1 GORISCV64 Environment Variable

Controls the minimum RISC-V ISA profile for generated code. Invalid values produce a fatal build error.

Value Meaning Default
rva20u64 RVA20U64 mandatory extensions only Yes
rva22u64 RVA22U64 mandatory extensions –
rva23u64 RVA23U64 mandatory extensions (Go 1.23+) –

The value is passed to the assembler as -D GORISCV64_rva20u64 (etc.) so assembly can perform conditional compilation per profile.

5.2 Build Commands

Native build on a riscv64 host:

cd src && ./all.bash

Cross-compile from x86-64 (CGo disabled):

export GOOS=linux GOARCH=riscv64 GORISCV64=rva20u64 CGO_ENABLED=0
cd src && ./make.bash

Cross-compile with CGo (requires riscv64 C toolchain):

export GOOS=linux GOARCH=riscv64 CGO_ENABLED=1
export CC_FOR_TARGET=riscv64-linux-gnu-gcc
cd src && ./make.bash

5.3 Bootstrap Compiler Requirements

Go 1.4 does not support linux/riscv64. A newer binary release or cross-compiled bootstrap tree is required. General rule: Go 1.N requires Go 1.(N-2, rounded to even) as bootstrap.

5.4 C Compiler Requirements

  • CGo requires a C compiler. Typical cross-compiler: riscv64-linux-gnu-gcc (Debian package: gcc-riscv64-linux-gnu).
  • Cross-compilation disables cgo by default unless CGO_ENABLED=1 is explicitly set.
  • freebsd/riscv64 CGo is marked supported in the platform matrix but the port is Broken (issue #76475).

6. Feature Coverage and Gap Analysis vs arm64 and amd64

6.1 Build Modes

Build mode linux/riscv64 linux/arm64 Notes
exe (default) Yes Yes –
pie (external linker) Yes Yes External linker required
pie (internal linker) No Yes Blocked; CLs 741860+742200 pending
plugin Yes Yes Added Go 1.25 (CL 420114, merged 2025-02-20)
shared No Yes Not implemented
c-archive Yes Yes –
c-shared Yes Yes –

6.2 Sanitizers and Instrumentation

Feature linux/riscv64 linux/arm64 Notes
Race detector (-race) Yes Yes Builder too slow for regular racebuild (#78258)
Address sanitizer (-asan) Yes Yes TestASAN failures reported (#57691, open)
Memory sanitizer (-msan) No Yes Requires compiler-rt support; not available for riscv64
Thread sanitizer (TSAN) Partial Yes TestTSAN/tsan8 failing (#76816, open)
Fuzzing instrumentation No Yes riscv64 excluded from FuzzInstrumented list (issue #14565 TODO in source)
DWARF prologue_end Yes Yes Added Oct 2024 (commit b45c7f1)

6.3 Crypto and FIPS

Feature linux/riscv64 linux/arm64 Notes
Pure-Go crypto (stdlib) Yes Yes –
Scalar assembly crypto (sha256, sha512) Yes Yes riscv64 uses Zbb rotation, added Go 1.23
Vector/SIMD crypto (AES, GCM, ChaCha20) No Yes No Zvkned/Zvknha/b assembly yet
BoringCrypto (GOEXPERIMENT=boringcrypto) No Yes No goboringcrypto_linux_riscv64.syso exists
FIPS140 with -buildmode=pie Broken Yes Issue #74683, fix CLs posted but not merged
x/crypto SIMD paths (ChaCha20, Poly1305) No Yes Pure Go fallback used; arm64/ppc64x/s390x have SIMD

6.4 Performance vs arm64

The only quantified comparison in the research findings comes from issue #77541 (Feb 2026):

  • ~20-40% execution slowdown on riscv64 vs arm64 on CPU-intensive workloads, measured via golang.org/x/benchmarks Bent suite on Go 1.25.6 with GORISCV64=rva23u64.
  • Root cause: RISC-V’s 12-bit signed immediate range forces 3 instructions per large-stack-offset access where ARM64 uses 1. The SSA backend treats these multi-instruction sequences as cheap to rematerialize, causing them to be recomputed every loop iteration.
  • Affected workloads: wazero interpreter benchmarks (string_manipulation_size_50, random_mat_mul_size_20), kanzi-go SBRT Transform hot loops.

The crypto/sha256 assembler optimization (commit 6d55a017, Go 1.23) measured on a StarFive VisionFive 2:

Benchmark Before After Delta
Hash8Bytes/New 7.820 us 5.193 us -33.6%
Hash1K/New 108.03 us 66.12 us -38.8%
Hash8K/New 808.5 us 493.0 us -39.0%
Hash1K throughput 9.041 MiB/s 14.772 MiB/s +63.4%

The vectorized internal/bytealg memequal (commit 75ea2d05, requires GORISCV64=rva23u64) measured on a Banana Pi F3:

Benchmark Before After Delta
Equal/4K 925.5 ns 561.4 ns -39.3%
Equal/4M 3.110 ms 2.463 ms -20.8%
EqualBothUnaligned/4096_1 956.6 ns 571.4 ns -40.3%
Geomean timing – – -13.9%
Geomean throughput – – +17.2%

Data not available: no published full-suite comparison of Go riscv64 vs arm64 across a representative application workload (e.g., HTTP server throughput, JSON parsing, GC-heavy workloads).

7. CI/CD Infrastructure

Go does not use GitHub Actions, .cirrus.yml, Jenkinsfile, or .travis.yml. The .github/ directory contains only ISSUE_TEMPLATE/, CODE_OF_CONDUCT.md, PULL_REQUEST_TEMPLATE, and SUPPORT.md – no workflow files exist.

All CI runs via the build.golang.org coordinator, configured in golang.org/x/build/dashboard/builders.go.

7.1 Active riscv64 Builders

All RISC-V builders are reverse buildlets running on physical hardware – no QEMU, no cloud VMs.

Builder name Hardware RAM/Cores Owner OS Timeout scale
linux-riscv64-unmatched SiFive HiFive Unmatched 16 GB, 4 cores mengzhuo (PLCT Lab) Linux 4x
linux-riscv64-jsing SiFive HiFive Unleashed 8 GB, 4 cores 4a6f656c (Joel Sing) Linux 4x
freebsd-riscv64-unmatched SiFive HiFive Unmatched 16 GB, 4 cores, FreeBSD 13.1-RELEASE mengzhuo (PLCT Lab) FreeBSD 4x
openbsd-riscv64-jsing physical reverse buildlet – 4a6f656c (Joel Sing) OpenBSD 3x

All builders apply riscvDistTestPolicy, which skips the api and reboot dist tests (same policy as MIPS). linux-riscv64-unmatched and freebsd-riscv64-unmatched use a private Go proxy (builder is behind a firewall).

Three of mengzhuo’s linux-riscv64-rva22u64 Banana Pi F3 bots (bbw-1, bbw-2, bbw-3) are currently broken (#79067, #79068, #79069, opened 2026-04-30).

7.2 Cross-Compilation Builders (no execution) 

addMiscCompile("freebsd", "riscv64")
addMiscCompileGo1(23, "openbsd", "riscv64", "-go1.23")
addMiscCompile("linux", "riscv64")

Note: golang.org/x/build itself is excluded from riscv64 misc-compile due to issue #58307.

7.3 LUCI Migration Status

riscv64 builders are not yet migrated to LUCI, unlike ppc64, loong64, and wasm which have been ported. All riscv64 CI remains on the old build.golang.org coordinator system [NEEDS VERIFICATION].

7.4 RISE Runners

RISE provides free native RISC-V CI on GitHub Actions (ubuntu-24.04-riscv label, Scaleway EM-RV1 hardware). As of the May 2026 “six weeks in” report, the Go upstream project is not listed among the 197 organizations using RISE RISC-V Runners for its own CI. The RISE blog post from September 2024 confirms Go received Scaleway bare-metal RISC-V infrastructure for development use.

8. Distribution and Release Status

Source riscv64 Present Version / Notes
go.dev/dl (official upstream) Yes go1.26.4.linux-riscv64.tar.gz, go1.25.11.linux-riscv64.tar.gz, go1.26.4.openbsd-riscv64.tar.gz, go1.25.11.freebsd-riscv64.tar.gz
Arch Linux RISC-V mirror Yes go-2:1.26.4-1-riscv64.pkg.tar.zst (40 MB), built 2026-06-03
Debian (buildd) Yes golang-defaults 2:1.26~1, status: Installed, built on rv-manda-04
Ubuntu 24.04 Noble Yes golang-1.22 stack, riscv64 listed as supported arch
GitHub release assets N/A Go does not ship binaries as GitHub release assets

linux/riscv64 binaries have been available from go.dev/dl since Go 1.21, per the RISE blog post “Advancing Go on RISC-V” (April 2025).

9. Dependencies

9.1 Go Module Dependencies (golang.org/x/*)

Go is largely self-hosted with few external dependencies when built with CGO_ENABLED=0.

Module Role riscv64 Status Notes
golang.org/x/crypto Extended crypto (ChaCha20, Poly1305, Curve25519, BLAKE2b) used directly by stdlib Builds (pure Go fallback) No riscv64 assembly for ChaCha20/Poly1305/Curve25519; arm64/ppc64x/s390x have SIMD paths
golang.org/x/net HTTP/2, QUIC, DNS, websocket Builds, passes No known riscv64-specific open issues
golang.org/x/sys Low-level OS syscall wrappers Builds, passes Two abandoned PRs from 2019 (epoll_event padding fix, endian_little tag) – whether underlying issues were resolved through another path requires verification [NEEDS VERIFICATION]
golang.org/x/text Unicode and text processing Builds, passes No known riscv64-specific issues

9.2 Optional C / Platform Dependencies

Dependency Role riscv64 Status Notes
BoringCrypto (google/boringssl .syso) FIPS-validated crypto backend (GOEXPERIMENT=boringcrypto) Not supported No goboringcrypto_linux_riscv64.syso exists; only linux/amd64 and linux/arm64 have pre-compiled .syso files
glibc System C library for cgo and dynamic linking Functional since glibc 2.27 (2018) –
OpenSSL (GODEBUG=fips140=on) FIPS crypto backend alternative Builds where OpenSSL 3.x is available Depends on OpenSSL riscv64 assembly completeness
C compiler (gcc/clang) Required for cgo builds only Functional Both gcc and clang support riscv64

10. Ecosystem Status

10.1 RISE Project Involvement

RISE funded RP001: Accelerate the Go Runtime on RISC-V, executed by Ludovic Henry and Mark Ryan (RIVOS Inc.). Deliverables documented in the April 2025 RISE blog post:

  • Vector ISA assembler support (integer arithmetic, FP ops, bitwise ops)
  • Dynamic runtime probing for available extensions (riscv_hwprobe)
  • Vectorized internal/bytealg (memory equality)
  • Build-time RISC-V profiles (RVA20, RVA22, RVA23)
  • Reduced instruction count via Bitmanip extension
  • Handcoded riscv64 assembler routines for math/big
  • Scalar assembler routines for md5, sha256, sha512
  • Plugin support for riscv64

RISE also provided Scaleway EM-RV1 bare-metal RISC-V CI infrastructure to the Go project (September 2024).

10.2 Key Active Contributors

Contributor Handle Affiliation Role
Meng Zhuo @mengzhuo PLCT Lab linux-riscv64-unmatched builder owner (x2); freebsd-riscv64-unmatched builder owner; high commit volume in obj/riscv
Joel Sing @4a6f656c Independent/OpenBSD linux-riscv64-joelsing and openbsd-riscv64-jsing builder owner; highest commit count in obj/riscv in research period
Mark Ryan @markdryan Data not available: company affiliation not found in research Active assembler contributor (CSR maps, vector fixes, documentation)
Tobias Klauser @tklauser Cilium/Isovalent Authored first RISC-V commits (arch reservation, ELF relocations)

11. Known Bugs and Active Issues

11.1 Open Correctness Bugs

Issue Title Severity Status
#78161 runtime: memory corruption leading to panic on linux/riscv64 Critical Open, Backlog, no assignee, help wanted. Compiler inlining miscompile on riscv64 (workaround: -gcflags '-l'). Actively blocking Alpine Linux package builds.
#74683 FIPS140 broken on RISC-V with -buildmode=pie Critical (FIPS deployments) Open, Backlog, assigned @mengzhuo. Fix CLs posted (CL 741860, 742200, 748040) and partially verified on MilkV Megrez, but binary still crashes at runtime in a later test; not merged.
#79275 cmd/link: J-type instruction relocation offset out of range High (build failure) Open, assigned @cherrymui. Fix CL 777120 (ByteDance) passed TryBot on PS2 (2026-05-20); awaiting Code-Review +2 from Cherry Mui or Joel Sing.
#68862 runtime: SIGSEGV in preemptone (riscv64) High Open, assigned @mengzhuo. Root cause: faulty BananaPi-F3/SpacemiT K1 SoC builder hardware with kernel-level mmap hang bug on kernel 6.6.36. Blocked on SpacemiT kernel fix.
#76816 TestTSAN/tsan8 failed on riscv64 Medium Open
#57691 runtime: TestASAN fails with SEGV on linux/riscv64 Medium Open (since Jan 2023)
#64791 syscall: TestExec failures with SIGSEGV on riscv64 Medium Open

11.2 Open Performance Issues

Issue Title Impact Status
#77541 Instruction bloat in hot loops – large stack frame offsets ~20-40% vs arm64 Open, NeedsInvestigation
#79298 Redundant LUI+ADD recomputation for large riscv stack offsets Structural inefficiency, ~10 wasted instructions per access sequence Open
#78258 linux-riscv64 builder too slow to run racebuild Blocks race-enabled testing Open

11.3 Open Feature / Infrastructure Issues

Issue Title Notes
#79997 internal/bytealg: optimize indexbyte_riscv64.s PR #79997 open
#79584 cmd/compile: add intrinsic rule for sync atomic and/or 32/64 on RISCV64 PR #79584 open, one unresolved Gerrit comment
#78918 hash/crc32: add crc32 assembly support for riscv64 PR #78918 open
#78515 cmd/compile: implement jump table on riscv64 PR #78515 open, has CR+2 [NEEDS VERIFICATION]
#77328 cmd/internal/obj/riscv: add Zvkned extension support Open, PR #77326 previously abandoned
#76475 build: freebsd/riscv64 port is broken Open
#76065 proposal: add flag for riscv optional extension support Open
#75577 Zicond codegen Merged 2026-02-24 (Go 1.27)
#64074 runtime: implement stackcheck for riscv64 PR open since Nov 2023, has CR+2 [NEEDS VERIFICATION]
#79069/68/67 x/build: bots linux-riscv64-rva22u64-bbw-1/2/3 broken Open since April 2026

11.4 Notably Closed/Fixed Bugs

Issue Title Resolution
#64917 cmd/compile: uint32(math.NaN()) returns -1 on riscv64 Fixed Jan 2024 – NaN float-to-uint32 gave wrong result unique to riscv64
#74606 cmd/compile: riscv performance regression Fixed Jul 2025 – inlining heuristic caused ~4x benchmark variance
#76654 Incorrect use of T0/X5 register causing RAS mismatch Fixed (Go 1.27)
#79270 plugin: build failure on riscv64 Fixed 2026-05-19
#78045 go1.26 SIGILL on riscv64 with vector support Fixed
#77209 cmd/link: wrong dynamic loader path on Linux riscv64 Fixed

12. Objections and Upstream Blockers

Objection 1: The port is secondary tier – a broken build does not block releases. Assessment: True. This is the correct characterization of the current status. The Go team has accepted this explicitly. Breakage goes to Backlog, not to a release gate. The practical consequence is that issues like #78161 (memory corruption) and #74683 (FIPS PIE broken) may remain open across multiple release cycles. Engineering leadership must weigh whether secondary-tier status is acceptable for production deployments or whether investment is needed to drive first-class status – which would require Google buy-in.

Objection 2: BoringCrypto is unavailable on riscv64. Assessment: Confirmed. GOEXPERIMENT=boringcrypto has no riscv64 .syso. This blocks any deployment that mandates FIPS using the BoringCrypto path. The alternative FIPS path (GOFIPS140=v1.0.0 with the native Go FIPS module) is broken with -buildmode=pie on riscv64 (issue #74683). Fix CLs exist (from Joel Sing) but are not merged as of June 2026. A deployment requiring both FIPS and PIE on riscv64 is currently not possible with the Go toolchain.

Objection 3: There is a structural 20-40% performance gap vs arm64 on CPU-intensive workloads. Assessment: Confirmed (single source: issue #77541). The root cause is architectural – RISC-V’s narrow immediate range combined with the current SSA cost model. Two open issues (#77541, #79298) document the problem. No fix CL has been posted. This is a compiler engineering problem, not a hardware limitation, and is addressable with SSA improvements.

Objection 4: The CI builders are fragile community-donated hardware. Assessment: Confirmed. Three of the four riscv64 builders are owned by a single individual (mengzhuo/PLCT Lab). The BananaPi-F3 hardware has triggered hardware-level mmap bugs (#68862). The freebsd/riscv64 port is formally broken (#76475). If mengzhuo’s machines go offline, linux/riscv64 CI coverage drops to a single SiFive HiFive Unleashed (8 GB, 4 cores) owned by Joel Sing. The builder timeout scale of 4x already indicates the hardware is marginal.

Objection 5: Several significant PRs have stalled. Assessment: Confirmed. PRs for jump tables (#78515, CR+2 but not merged), stackcheck (#64074, open since November 2023), Zba compiler support (#76211, open since November 2025), unaligned memory access optimization (#77207, on Hold), and crc32 assembly (#78918) are all pending without active reviewer engagement. This reflects the limited bandwidth of the riscv64 maintainer team.

13. Investment Analysis

13.1 Functional Enablement

Work Item Current State Required Work Priority
Fix FIPS140 + PIE on riscv64 (#74683) Fix CLs exist (CL 741860, 742200, 748040), partially verified, not merged Review and submit existing CLs; validate on additional hardware Critical
Fix memory corruption / inlining miscompile (#78161) Open, no CL, help wanted Bisect compiler inlining path on riscv64; fix SSA or ABI handling Critical
Fix J-type relocation overflow (#79275) Fix CL 777120 passed TryBot; awaiting +2 Reviewer attention from Cherry Mui or Joel Sing High
Internal PIE linker support CLs 741860+742200 prerequisite for FIPS fix Reviewer bandwidth High
Repair broken CI builders (#79067-69) 3 of 4 linux builders broken Hardware replacement or migration to cloud (Scaleway EM-RV1 via RISE) High
freebsd/riscv64 port (#76475) Broken Diagnose and fix; evaluate whether to promote or remove Medium
BoringCrypto riscv64 Not supported Build goboringcrypto_linux_riscv64.syso from BoringSSL; FIPS validation scope TBD Medium (FIPS-mandatory deployments)

13.2 Performance Optimization

Work Item Current State Required Work Priority
Fix instruction bloat in hot loops (#77541, #79298) Root cause identified, no CL SSA cost model improvements; LICM for large stack frame base addresses High
Land jump table codegen (#78515) Has CR+2, not merged Reviewer submission High
Land atomic intrinsics for sync/atomic And/Or (#79584) PR open, 1 unresolved comment Minor iteration + reviewer Medium
Land Zba compiler codegen (#76211) PR open Nov 2025 Reviewer attention Medium
Vectorized crypto via Zvkned/Zvknha/b (AES, SHA via vector) No CL exists (#77328 for Zvkned assembler) Write assembly; issue #79958 (Zvbb SIMD) marked “Not Planned” Medium
Optimize x/crypto (ChaCha20, Poly1305) for riscv64 Pure Go fallback only Write assembly similar to arm64 implementation Medium
Optimize hash/crc32 (#78918) PR open Review and merge Low
Optimize internal/bytealg indexbyte (#79997) PR open Review and merge Low
Optimize P256 crypto (#77069) PR open Review and merge Low

13.3 CI/CD Infrastructure

Work Item Current State Required Work Priority
Repair broken bots (#79067-69) 3 bots offline Replace BananaPi-F3 hardware or migrate to Scaleway EM-RV1 via RISE High
Enable racebuild on riscv64 (#78258) Builder times out (~2h13m) Faster hardware (Scaleway EM-RV1) or parallelism Medium
LUCI migration riscv64 not yet migrated Port builder definitions; coordinate with Google infra team Low
Add openbsd/riscv64 LUCI builder (#73569) Builder missing Provision hardware + LUCI registration Low
Add freebsd/riscv64 LUCI builder (#73568) Builder missing Depends on port stability Low

13.4 Ecosystem Enablement

Work Item Current State Required Work Priority
Fuzzing instrumentation on riscv64 Not implemented Port coverage-guided fuzzing (afl/pcguard) to riscv64 Medium
MSan support on riscv64 Not supported Requires compiler-rt port; upstream to llvm and Go Low
Shared library build mode (-buildmode=shared) Not supported Linker work Low

13.5 Summary Table

Area Work Item Effort (person-weeks) Owner Priority
Functional Fix FIPS140 + PIE (#74683) 2-4 (review + validate existing CLs) Reviewer (Cherry Mui / Joel Sing) + QA Critical
Functional Fix memory corruption / inlining miscompile (#78161) 4-8 (bisect + fix) Compiler engineer with riscv64 knowledge Critical
Functional Fix J-type relocation overflow (#79275) 1 (reviewer submission) Cherry Mui / Joel Sing High
Infrastructure Repair broken CI bots (#79067-69) 1-2 (hardware + config) mengzhuo / RISE High
Performance Fix instruction bloat in hot loops (#77541, #79298) 6-10 (SSA cost model) Go compiler engineer (riscv64) High
Functional Land jump table codegen (#78515) 1 (reviewer submission) Joel Sing / Cherry Mui High
Performance Land Zba codegen (#76211) 1 (reviewer) riscv64 maintainer Medium
Performance Land atomic intrinsics (#79584) 1 (minor iteration + review) newborn22 + reviewer Medium
Performance Vectorized crypto (Zvkned/Zvknha/b) 8-16 (write assembly + tests) Crypto + riscv64 engineer Medium
Performance x/crypto SIMD (ChaCha20, Poly1305) 4-8 Go crypto engineer Medium
Functional BoringCrypto riscv64 .syso 4-8 + FIPS validation (separate) BoringSSL + FIPS lab Medium
Infrastructure Enable racebuild on riscv64 (#78258) 1-2 (hardware) mengzhuo / RISE Medium
Functional Fuzzing instrumentation 8-16 Go runtime engineer Medium
Infrastructure LUCI migration 2-4 Google infra + riscv64 maintainer Low

14. Updates

No updates yet – initial report dated 2026-06-17.

15. References