Promote riscv64-unknown-linux-musl to tier 2 with host tools

eshattow · E Shattow · commit 3e5f43a176dd · 2026-07-08T10:12:24.000-07:00
Implements MCP 982 via issue 156191
diff --git a/compiler/rustc_target/src/spec/targets/riscv64gc_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/targets/riscv64gc_unknown_linux_musl.rs
@@ -10,7 +10,7 @@ pub(crate) fn target() -> Target {
         metadata: TargetMetadata {
             description: Some("RISC-V Linux (kernel 4.20, musl 1.2.5)".into()),
             tier: Some(2),
-            host_tools: Some(false),
+            host_tools: Some(true),
             std: Some(true),
         },
         pointer_width: 64,
diff --git a/src/bootstrap/src/core/build_steps/llvm.rs b/src/bootstrap/src/core/build_steps/llvm.rs
@@ -248,6 +248,7 @@ pub(crate) fn is_ci_llvm_available_for_target(
         ("powerpc64le-unknown-linux-gnu", false),
         ("powerpc64le-unknown-linux-musl", false),
         ("riscv64gc-unknown-linux-gnu", false),
+        ("riscv64gc-unknown-linux-musl", false),
         ("s390x-unknown-linux-gnu", false),
         ("x86_64-pc-windows-gnullvm", false),
         ("x86_64-unknown-freebsd", false),
diff --git a/src/bootstrap/src/core/download.rs b/src/bootstrap/src/core/download.rs
@@ -481,6 +481,7 @@ pub(crate) fn is_download_ci_available(target_triple: &str, llvm_assertions: boo
         "powerpc64le-unknown-linux-gnu",
         "powerpc64le-unknown-linux-musl",
         "riscv64gc-unknown-linux-gnu",
+        "riscv64gc-unknown-linux-musl",
         "s390x-unknown-linux-gnu",
         "x86_64-apple-darwin",
         "x86_64-pc-windows-gnu",
diff --git a/src/ci/docker/README.md b/src/ci/docker/README.md
@@ -462,6 +462,22 @@ For targets: `riscv64-unknown-linux-gnu`
 - C compiler > gcc version = 8.5.0
 - C compiler > C++ = ENABLE -- to cross compile LLVM
 
+### `riscv64-unknown-linux-musl.defconfig`
+
+For targets: `riscv64-unknown-linux-musl`
+
+- Path and misc options > Prefix directory = /x-tools/${CT\_TARGET}
+- Path and misc options > Use a mirror = ENABLE
+- Path and misc options > Base URL = https://ci-mirrors.rust-lang.org/rustc
+- Target options > Target Architecture = riscv
+- Target options > Bitness = 64-bit
+- Operating System > Target OS = linux
+- Operating System > Linux kernel version = 4.20.17
+- Binary utilities > Version of binutils = 2.40
+- C-library > musl version = 1.2.5
+- C compiler > gcc version = 8.5.0
+- C compiler > C++ = ENABLE -- to cross compile LLVM
+
 ### `s390x-linux-gnu.defconfig`
 
 For targets: `s390x-unknown-linux-gnu`
diff --git a/src/ci/docker/host-x86_64/dist-riscv64-linux-gnu/Dockerfile b/src/ci/docker/host-x86_64/dist-riscv64-linux-gnu/Dockerfile
@@ -12,7 +12,7 @@ RUN sh /scripts/rustbuild-setup.sh
 WORKDIR /tmp
 
 COPY scripts/crosstool-ng-build.sh /scripts/
-COPY host-x86_64/dist-riscv64-linux/riscv64-unknown-linux-gnu.defconfig /tmp/crosstool.defconfig
+COPY host-x86_64/dist-riscv64-linux-gnu/riscv64-unknown-linux-gnu.defconfig /tmp/crosstool.defconfig
 RUN /scripts/crosstool-ng-build.sh
 
 COPY scripts/sccache.sh /scripts/
diff --git a/src/ci/docker/host-x86_64/dist-riscv64-linux-gnu/riscv64-unknown-linux-gnu.defconfig b/src/ci/docker/host-x86_64/dist-riscv64-linux-gnu/riscv64-unknown-linux-gnu.defconfig
diff --git a/src/ci/docker/host-x86_64/dist-riscv64-linux-musl/Dockerfile b/src/ci/docker/host-x86_64/dist-riscv64-linux-musl/Dockerfile
@@ -0,0 +1,39 @@
+FROM ubuntu:22.04
+
+COPY scripts/cross-apt-packages.sh /scripts/
+RUN sh /scripts/cross-apt-packages.sh
+
+COPY scripts/crosstool-ng.sh /scripts/
+COPY scripts/crosstool-ng-sha256-20260705.diff /scripts/
+RUN sh /scripts/crosstool-ng.sh
+
+COPY scripts/rustbuild-setup.sh /scripts/
+RUN sh /scripts/rustbuild-setup.sh
+
+WORKDIR /tmp
+
+COPY scripts/crosstool-ng-build.sh /scripts/
+COPY host-x86_64/dist-riscv64-linux-musl/riscv64-unknown-linux-musl.defconfig /tmp/crosstool.defconfig
+RUN /scripts/crosstool-ng-build.sh
+
+COPY scripts/sccache.sh /scripts/
+RUN sh /scripts/sccache.sh
+
+ENV PATH=$PATH:/x-tools/riscv64-unknown-linux-musl/bin
+
+ENV CC_riscv64gc_unknown_linux_musl=riscv64-unknown-linux-musl-gcc \
+    AR_riscv64gc_unknown_linux_musl=riscv64-unknown-linux-musl-ar \
+    CXX_riscv64gc_unknown_linux_musl=riscv64-unknown-linux-musl-g++
+
+ENV HOSTS=riscv64gc-unknown-linux-musl
+ENV TARGETS=riscv64gc-unknown-linux-musl
+
+ENV RUST_CONFIGURE_ARGS="--enable-extended \
+    --enable-full-tools \
+    --enable-profiler \
+    --enable-sanitizers \
+    --disable-docs \
+    --set target.riscv64gc-unknown-linux-musl.crt-static=false \
+    --musl-root-riscv64gc=/x-tools/riscv64-unknown-linux-musl/riscv64-unknown-linux-musl/sysroot/usr"
+
+ENV SCRIPT="python3 ../x.py dist --target $TARGETS --host $HOSTS"
diff --git a/src/ci/docker/host-x86_64/dist-riscv64-linux-musl/riscv64-unknown-linux-musl.defconfig b/src/ci/docker/host-x86_64/dist-riscv64-linux-musl/riscv64-unknown-linux-musl.defconfig
@@ -0,0 +1,16 @@
+CT_CONFIG_VERSION="4"
+CT_PREFIX_DIR="/x-tools/${CT_TARGET}"
+CT_USE_MIRROR=y
+CT_MIRROR_BASE_URL="https://ci-mirrors.rust-lang.org/rustc"
+CT_VERIFY_DOWNLOAD_DIGEST_SHA256=y
+CT_ARCH_RISCV=y
+CT_ARCH_USE_MMU=y
+CT_ARCH_64=y
+CT_ARCH_ARCH="rv64gc"
+CT_KERNEL_LINUX=y
+CT_LINUX_V_4_20=y
+CT_LIBC_MUSL=y
+CT_BINUTILS_V_2_40=y
+CT_MUSL_V_1_2_5=y
+CT_GCC_V_8=y
+CT_CC_LANG_CXX=y
diff --git a/src/ci/github-actions/jobs.yml b/src/ci/github-actions/jobs.yml
@@ -270,7 +270,10 @@ auto:
   - name: dist-powerpc64le-linux-musl
     <<: *job-linux-4c
 
-  - name: dist-riscv64-linux
+  - name: dist-riscv64-linux-gnu
+    <<: *job-linux-4c
+
+  - name: dist-riscv64-linux-musl
     <<: *job-linux-4c
 
   - name: dist-s390x-linux
diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
@@ -105,6 +105,7 @@ target | notes
 [`powerpc64le-unknown-linux-gnu`](platform-support/powerpc64le-unknown-linux-gnu.md) | PPC64LE Linux (kernel 3.10+, glibc 2.17)
 [`powerpc64le-unknown-linux-musl`](platform-support/powerpc64le-unknown-linux-musl.md) | PPC64LE Linux (kernel 4.19+, musl 1.2.5)
 [`riscv64gc-unknown-linux-gnu`](platform-support/riscv64gc-unknown-linux-gnu.md) | RISC-V Linux (kernel 4.20+, glibc 2.29)
+[`riscv64gc-unknown-linux-musl`](platform-support/riscv64gc-unknown-linux-musl.md) | RISC-V Linux (kernel 4.20+, musl 1.2.5)
 [`s390x-unknown-linux-gnu`](platform-support/s390x-unknown-linux-gnu.md) | S390x Linux (kernel 3.2+, glibc 2.17)
 [`x86_64-apple-darwin`](platform-support/apple-darwin.md) | 64-bit macOS (10.12+, Sierra+)
 [`x86_64-pc-windows-gnullvm`](platform-support/windows-gnullvm.md) | 64-bit x86 MinGW (Windows 10+), LLVM ABI
@@ -196,7 +197,6 @@ target | std | notes
 [`riscv32imafc-unknown-none-elf`](platform-support/riscv32-unknown-none-elf.md) | * | Bare RISC-V (RV32IMAFC ISA)
 [`riscv32imc-unknown-none-elf`](platform-support/riscv32-unknown-none-elf.md) | * | Bare RISC-V (RV32IMC ISA)
 [`riscv64a23-unknown-linux-gnu`](platform-support/riscv64a23-unknown-linux-gnu.md) | ✓ | RISC-V Linux (kernel 6.8.0+, glibc 2.39)
-[`riscv64gc-unknown-linux-musl`](platform-support/riscv64gc-unknown-linux-musl.md) | ✓ |RISC-V Linux (kernel 4.20+, musl 1.2.5)
 `riscv64gc-unknown-none-elf` | * | Bare RISC-V (RV64IMAFDC ISA)
 [`riscv64im-unknown-none-elf`](platform-support/riscv64im-unknown-none-elf.md) | * | Bare RISC-V (RV64IM ISA)
 `riscv64imac-unknown-none-elf` | * | Bare RISC-V (RV64IMAC ISA)
diff --git a/src/doc/rustc/src/platform-support/riscv64gc-unknown-linux-musl.md b/src/doc/rustc/src/platform-support/riscv64gc-unknown-linux-musl.md
@@ -1,6 +1,6 @@
 # riscv64gc-unknown-linux-musl
 
-**Tier: 2**
+**Tier: 2 (with Host Tools)**
 
 Target for RISC-V Linux programs using musl libc.
 
@@ -17,29 +17,38 @@ Building the target itself requires a RISC-V compiler that is supported by `cc-r
 
 The target can be built by enabling it for a `rustc` build.
 
+These targets are distributed through `rustup`, and otherwise require no
+special configuration.
+
+If you need to build your own Rust then the targets can be enabled in
+`bootstrap.toml`. For example:
+
 ```toml
 [build]
 target = ["riscv64gc-unknown-linux-musl"]
 ```
 
-Make sure your C compiler is included in `$PATH`, then add it to the `bootstrap.toml`:
-
-```toml
-[target.riscv64gc-unknown-linux-musl]
-cc = "riscv64-linux-gnu-gcc"
-cxx = "riscv64-linux-gnu-g++"
-ar = "riscv64-linux-gnu-ar"
-linker = "riscv64-linux-gnu-gcc"
-```
 
 ## Building Rust programs
 
 This target are distributed through `rustup`, and otherwise require no
 special configuration.
 
-## Cross-compilation
+On a RISC-V host, the `riscv64gc-unknown-linux-musl` target should be
+automatically installed and used by default.
+
+On a non-RISC-V host, add the target:
+
+```bash
+rustup target add riscv64gc-unknown-linux-musl
+```
+
+Then cross compile crates with:
+
+```bash
+cargo build --target riscv64gc-unknown-linux-musl
+```
 
-This target can be cross-compiled from any host.
 
 ## Testing
 
