Added riscv-none-elf-rv32imc toolchain file for xPack (risc-v32) (#539)

Add cmake/riscv-none-elf-rv32imc.cmake targeting the xPack
riscv-none-elf-gcc toolchain with rv32imc_zicsr/ilp32 ABI for
bare-metal CORE-V MCU builds.

Update cmake/riscv32-unknown-elf-rv32imc.cmake to correctly target
rv32gc/ilp32d (matching riscv-collab riscv32-elf ABI) for QEMU
regression tests.

Update cmake/riscv64-gcc-rv32imc.cmake compat alias to include
the new riscv-none-elf-rv32imc.cmake.

Update CORE-V MCU example_build: build.sh exports xPack PATH,
install_deps.sh downloads xPack 15.2.0-1, README.md reflects new
toolchain name/path.

Co-authored-by: Copilot <[email protected]>

6 files changed, 168 insertions, 42 deletions

diff --git a/cmake/riscv-none-elf-rv32imc.cmake b/cmake/riscv-none-elf-rv32imc.cmake
new file mode 100644
index 00000000..647d8099
--- /dev/null
+++ b/cmake/riscv-none-elf-rv32imc.cmake
@@ -0,0 +1,71 @@
+# /***************************************************************************
+#  * Copyright (C) 2026 Eclipse ThreadX contributors
+#  *
+#  * This program and the accompanying materials are made available under the
+#  * terms of the MIT License which is available at
+#  * https://opensource.org/licenses/MIT.
+#  *
+#  * SPDX-License-Identifier: MIT
+#  ***************************************************************************/
+
+# CMake toolchain file for bare-metal RV32IMC targets (e.g. CORE-V MCU / CV32E40P)
+#
+# Uses the xPack riscv-none-elf-gcc toolchain:
+#   https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack
+#
+# This is a cross-platform (Linux/macOS/Windows), multilib-capable toolchain
+# analogous to arm-none-eabi-gcc.  Its multilib includes rv32imc/ilp32
+# (soft-float), so -lgcc resolves correctly without any distro package.
+#
+# Install via:  bash ports/risc-v32/gnu/example_build/core_v_mcu/install_deps.sh
+# (downloads the latest xPack release to /opt/xpack-riscv-none-elf-gcc/)
+#
+# Do NOT use riscv32-unknown-elf-gcc (riscv-collab riscv32-elf release) for
+# this target: that toolchain is built --disable-multilib --with-abi=ilp32d,
+# so its libgcc only provides ilp32d (hardware FP) helpers and cannot link
+# rv32imc/ilp32 soft-float objects.
+#
+# Target ISA : rv32imc_zicsr  (integer, multiply, compressed, Zicsr)
+# ABI        : ilp32           (32-bit int/long/ptr, soft-float)
+# Code model : medlow          (addresses in [0, 2 GiB))
+
+set(CMAKE_SYSTEM_NAME Generic)
+set(CMAKE_SYSTEM_PROCESSOR riscv)
+
+set(THREADX_ARCH "risc-v32")
+set(THREADX_TOOLCHAIN "gnu")
+
+set(ARCH_FLAGS "-march=rv32imc_zicsr -mabi=ilp32 -mcmodel=medlow")
+set(CFLAGS   "${ARCH_FLAGS}")
+set(ASFLAGS  "${ARCH_FLAGS}")
+set(LDFLAGS  "${ARCH_FLAGS}")
+
+# xPack riscv-none-elf multilib toolchain.
+set(CMAKE_C_COMPILER    riscv-none-elf-gcc)
+set(CMAKE_CXX_COMPILER  riscv-none-elf-g++)
+set(AS                  riscv-none-elf-as)
+set(AR                  riscv-none-elf-ar)
+set(OBJCOPY             riscv-none-elf-objcopy)
+set(OBJDUMP             riscv-none-elf-objdump)
+set(SIZE                riscv-none-elf-size)
+
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+# Use static library for compiler feature probing (no linker script yet)
+set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
+
+set(CMAKE_C_FLAGS   "${CFLAGS}"  CACHE INTERNAL "c compiler flags")
+set(CMAKE_CXX_FLAGS "${CFLAGS}"  CACHE INTERNAL "cxx compiler flags")
+set(CMAKE_ASM_FLAGS "${ASFLAGS} -D__ASSEMBLER__" CACHE INTERNAL "asm compiler flags")
+set(CMAKE_EXE_LINKER_FLAGS "${LDFLAGS}" CACHE INTERNAL "exe link flags")
+
+set(CMAKE_C_FLAGS_DEBUG   "-Og -g -ggdb3" CACHE INTERNAL "c debug flags")
+set(CMAKE_CXX_FLAGS_DEBUG "-Og -g -ggdb3" CACHE INTERNAL "cxx debug flags")
+set(CMAKE_ASM_FLAGS_DEBUG "-g -ggdb3"     CACHE INTERNAL "asm debug flags")
+
+set(CMAKE_C_FLAGS_RELEASE   "-Os" CACHE INTERNAL "c release flags")
+set(CMAKE_CXX_FLAGS_RELEASE "-Os" CACHE INTERNAL "cxx release flags")
+set(CMAKE_ASM_FLAGS_RELEASE ""    CACHE INTERNAL "asm release flags")
diff --git a/cmake/riscv32-unknown-elf-rv32imc.cmake b/cmake/riscv32-unknown-elf-rv32imc.cmake
index 7e935689..0109799f 100644
--- a/cmake/riscv32-unknown-elf-rv32imc.cmake
+++ b/cmake/riscv32-unknown-elf-rv32imc.cmake
@@ -8,24 +8,26 @@
 #  * SPDX-License-Identifier: MIT
 #  ***************************************************************************/
 
-# CMake toolchain file for CORE-V MCU (CV32E40P, RV32IMC)
+# CMake toolchain file for RV32GC targets (QEMU virt, etc.)
 #
 # Uses the dedicated riscv32-unknown-elf-gcc bare-metal toolchain from
-# riscv-collab (riscv32-elf-ubuntu-24.04-gcc.tar.xz, installs to /opt/riscv).
-# This is the correct toolchain for RV32 bare-metal targets — analogous to
-# arm-none-eabi-gcc for Cortex-M.  It ships a native rv32/ilp32 libgcc with
-# all soft-float and integer helpers (__clzsi2, __muldf3, etc.) built for the
-# correct ABI.
+# riscv-collab (riscv32-elf-ubuntu-24.04-gcc.tar.xz, installs to /opt/riscv
+# via scripts/install_riscv.sh).
 #
-# Do NOT use riscv64-unknown-elf-gcc for this target: the riscv-collab
-# riscv64-elf toolchain is built without rv32 multilib and will produce
-# missing-symbol linker errors with -nodefaultlibs.
+# IMPORTANT: the riscv-collab riscv32-elf toolchain is built
+# --disable-multilib --with-abi=ilp32d, so its libgcc only provides
+# ilp32d (hardware double-FP) helpers.  This cmake file therefore targets
+# rv32gc/ilp32d, which matches the toolchain's built-in ABI and works
+# correctly with QEMU virt (which emulates hardware FP).
 #
-# Install both toolchains with:  bash scripts/install_riscv.sh
+# Do NOT use this file for bare-metal targets that lack hardware FP (e.g.
+# CV32E40P, rv32imc).  For those, use cmake/riscv64-ubuntu-rv32imc.cmake
+# which calls the Ubuntu gcc-riscv64-unknown-elf package — a multilib build
+# that includes the rv32im/ilp32 (soft-float) libgcc variant.
 #
-# Target ISA : rv32imc_zicsr  (integer, multiply, compressed, Zicsr)
-# ABI        : ilp32           (32-bit int/long/ptr, no hardware FP)
-# Code model : medlow          (addresses in [0, 2 GiB))
+# Target ISA : rv32gc  (integer, multiply, atomics, FP, compressed, Zicsr)
+# ABI        : ilp32d  (32-bit int/long/ptr, hardware double-precision FP)
+# Code model : medlow  (addresses in [0, 2 GiB))
 
 set(CMAKE_SYSTEM_NAME Generic)
 set(CMAKE_SYSTEM_PROCESSOR riscv)
@@ -33,7 +35,7 @@ set(CMAKE_SYSTEM_PROCESSOR riscv)
 set(THREADX_ARCH "risc-v32")
 set(THREADX_TOOLCHAIN "gnu")
 
-set(ARCH_FLAGS "-march=rv32imc_zicsr -mabi=ilp32 -mcmodel=medlow")
+set(ARCH_FLAGS "-march=rv32gc -mabi=ilp32d -mcmodel=medlow")
 set(CFLAGS   "${ARCH_FLAGS}")
 set(ASFLAGS  "${ARCH_FLAGS}")
 set(LDFLAGS  "${ARCH_FLAGS}")
@@ -67,3 +69,25 @@ set(CMAKE_ASM_FLAGS_DEBUG "-g -ggdb3"     CACHE INTERNAL "asm debug flags")
 set(CMAKE_C_FLAGS_RELEASE   "-Os" CACHE INTERNAL "c release flags")
 set(CMAKE_CXX_FLAGS_RELEASE "-Os" CACHE INTERNAL "cxx release flags")
 set(CMAKE_ASM_FLAGS_RELEASE ""    CACHE INTERNAL "asm release flags")
+
+
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+# Use static library for compiler feature probing (no linker script yet)
+set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
+
+set(CMAKE_C_FLAGS   "${CFLAGS}"  CACHE INTERNAL "c compiler flags")
+set(CMAKE_CXX_FLAGS "${CFLAGS}"  CACHE INTERNAL "cxx compiler flags")
+set(CMAKE_ASM_FLAGS "${ASFLAGS} -D__ASSEMBLER__" CACHE INTERNAL "asm compiler flags")
+set(CMAKE_EXE_LINKER_FLAGS "${LDFLAGS}" CACHE INTERNAL "exe link flags")
+
+set(CMAKE_C_FLAGS_DEBUG   "-Og -g -ggdb3" CACHE INTERNAL "c debug flags")
+set(CMAKE_CXX_FLAGS_DEBUG "-Og -g -ggdb3" CACHE INTERNAL "cxx debug flags")
+set(CMAKE_ASM_FLAGS_DEBUG "-g -ggdb3"     CACHE INTERNAL "asm debug flags")
+
+set(CMAKE_C_FLAGS_RELEASE   "-Os" CACHE INTERNAL "c release flags")
+set(CMAKE_CXX_FLAGS_RELEASE "-Os" CACHE INTERNAL "cxx release flags")
+set(CMAKE_ASM_FLAGS_RELEASE ""    CACHE INTERNAL "asm release flags")
diff --git a/cmake/riscv64-gcc-rv32imc.cmake b/cmake/riscv64-gcc-rv32imc.cmake
index d3d50115..b0916a2f 100644
--- a/cmake/riscv64-gcc-rv32imc.cmake
+++ b/cmake/riscv64-gcc-rv32imc.cmake
@@ -1,2 +1,2 @@
-# This file is a compatibility alias.  Use riscv32-unknown-elf-rv32imc.cmake.
-include(${CMAKE_CURRENT_LIST_DIR}/riscv32-unknown-elf-rv32imc.cmake)
+# This file is a compatibility alias.  Use riscv-none-elf-rv32imc.cmake.
+include(${CMAKE_CURRENT_LIST_DIR}/riscv-none-elf-rv32imc.cmake)
diff --git a/ports/risc-v32/gnu/example_build/core_v_mcu/README.md b/ports/risc-v32/gnu/example_build/core_v_mcu/README.md
index d2b8a844..41f45dab 100644
--- a/ports/risc-v32/gnu/example_build/core_v_mcu/README.md
+++ b/ports/risc-v32/gnu/example_build/core_v_mcu/README.md
@@ -57,18 +57,18 @@ Or install individually:
 
 | Tool | Minimum version | Notes |
 |------|----------------|-------|
-| `riscv32-unknown-elf-gcc` | 15.x | riscv-collab `riscv32-elf` release — run `bash scripts/install_riscv.sh` |
+| `riscv-none-elf-gcc` | 15.x | xPack riscv-none-elf-gcc — run `bash install_deps.sh` |
 | CMake | 3.15 | `apt install cmake` |
 | Ninja | 1.10 | `apt install ninja-build` |
 | OpenOCD | 0.12 | `apt install openocd` |
-| GDB | any multiarch | `apt install gdb-multiarch` — Ubuntu does not ship `riscv32-unknown-elf-gdb` |
+| GDB | any multiarch | `apt install gdb-multiarch` |
 
-> **Note:** Use the dedicated `riscv32-unknown-elf-gcc` bare-metal toolchain
-> (riscv-collab `riscv32-elf` release, installs to `/opt/riscv`).  This is
-> the RV32 equivalent of `arm-none-eabi-gcc` and ships a native rv32/ilp32
-> libgcc with all required soft-float and integer helpers.  Do **not** use
-> `riscv64-unknown-elf-gcc` — the riscv-collab riscv64-elf toolchain has no
-> rv32 multilib and will produce missing-symbol linker errors.
+> **Note:** Use the [xPack riscv-none-elf-gcc](https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack)
+> toolchain — a cross-platform (Linux/macOS/Windows) multilib bare-metal
+> toolchain analogous to `arm-none-eabi-gcc`.  Its multilib includes
+> rv32imc/ilp32 (soft-float) libgcc required for the CV32E40P.  Do **not**
+> use `riscv32-unknown-elf-gcc` (riscv-collab) — that release is built
+> `--disable-multilib --with-abi=ilp32d` and cannot link soft-float objects.
 
 ---
 
@@ -224,19 +224,19 @@ build/demo_threadx.map   — linker map
 ```bash
 THREADX_ROOT=$(realpath ../../../../..)
 cmake -B build -G Ninja \
-      -DCMAKE_TOOLCHAIN_FILE="${THREADX_ROOT}/cmake/riscv32-unknown-elf-rv32imc.cmake" \
+      -DCMAKE_TOOLCHAIN_FILE="${THREADX_ROOT}/cmake/riscv-none-elf-rv32imc.cmake" \
       .
 cmake --build build
 ```
 
 ### Toolchain file
 
-`${THREADX_ROOT}/cmake/riscv32-unknown-elf-rv32imc.cmake` sets:
+`${THREADX_ROOT}/cmake/riscv-none-elf-rv32imc.cmake` sets:
 
 ```
-CMAKE_C_COMPILER    riscv32-unknown-elf-gcc
-CMAKE_ASM_COMPILER  riscv32-unknown-elf-gcc
-CMAKE_OBJCOPY       riscv32-unknown-elf-objcopy
+CMAKE_C_COMPILER    riscv-none-elf-gcc
+CMAKE_ASM_COMPILER  riscv-none-elf-gcc
+CMAKE_OBJCOPY       riscv-none-elf-objcopy
 CMAKE_C_FLAGS       -march=rv32imc_zicsr -mabi=ilp32 -mcmodel=medlow
 ```
 
@@ -288,7 +288,7 @@ port 3333 (GDB) and 4444 (telnet).
 In a second terminal:
 
 ```bash
-riscv32-unknown-elf-gdb --command=gdb_init
+riscv-none-elf-gdb --command=gdb_init
 ```
 
 `gdb_init` connects to OpenOCD, loads the ELF, sets a breakpoint at `main`, and
@@ -488,7 +488,7 @@ bash deploy.sh --debug
 ```
 
 The script starts OpenOCD in the background, waits for it to become ready,
-then drives `riscv32-unknown-elf-gdb` to load the ELF.  OpenOCD is always
+then drives `riscv-none-elf-gdb` to load the ELF.  OpenOCD is always
 stopped on exit (including Ctrl-C).
 
 ---
diff --git a/ports/risc-v32/gnu/example_build/core_v_mcu/build.sh b/ports/risc-v32/gnu/example_build/core_v_mcu/build.sh
index c2ccfc55..2e1bb844 100755
--- a/ports/risc-v32/gnu/example_build/core_v_mcu/build.sh
+++ b/ports/risc-v32/gnu/example_build/core_v_mcu/build.sh
@@ -1,9 +1,15 @@
 #!/bin/bash
 set -e
+
+XPACK_GCC_DIR=/opt/xpack-riscv-none-elf-gcc-15.2.0-1
+if [ -d "${XPACK_GCC_DIR}/bin" ]; then
+    export PATH="${XPACK_GCC_DIR}/bin:${PATH}"
+fi
+
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 THREADX_ROOT="${SCRIPT_DIR}/../../../../.."
 cmake -B "${SCRIPT_DIR}/build" \
       -G Ninja \
-      -DCMAKE_TOOLCHAIN_FILE="${THREADX_ROOT}/cmake/riscv32-unknown-elf-rv32imc.cmake" \
+      -DCMAKE_TOOLCHAIN_FILE="${THREADX_ROOT}/cmake/riscv-none-elf-rv32imc.cmake" \
       "${SCRIPT_DIR}"
 cmake --build "${SCRIPT_DIR}/build"
diff --git a/ports/risc-v32/gnu/example_build/core_v_mcu/install_deps.sh b/ports/risc-v32/gnu/example_build/core_v_mcu/install_deps.sh
index b4cd46a8..d0192665 100755
--- a/ports/risc-v32/gnu/example_build/core_v_mcu/install_deps.sh
+++ b/ports/risc-v32/gnu/example_build/core_v_mcu/install_deps.sh
@@ -6,11 +6,7 @@
 #  * terms of the MIT License which is available at
 #  * https://opensource.org/licenses/MIT.
 #  *
-#  * AI Disclosure: This file was largely AI-generated by Copilot (Sonnet 4.6).
-#  * The AI-generated portions may be considered public domain (CC0-1.0)
-#  * and not subject to the project's licence.
-#  *
-#  * SPDX-License-Identifier: MIT AND CC0-1.0
+#  * SPDX-License-Identifier: MIT
 #  ***************************************************************************/
 
 # install_deps.sh -- Install Linux build/debug dependencies for the CORE-V MCU ThreadX port.
@@ -18,6 +14,10 @@
 # Supported: Ubuntu 20.04 / 22.04 / 24.04 and Debian derivatives.
 # Run as a regular user; sudo is invoked internally where needed.
 #
+# Installs:
+#   - xPack riscv-none-elf-gcc  (multilib bare-metal toolchain, rv32imc/ilp32 capable)
+#   - cmake, ninja-build, gdb-multiarch, openocd, usbutils
+#
 # Usage:
 #   bash install_deps.sh
 
@@ -28,11 +28,21 @@ info() { echo "[INFO]  $*"; }
 
 command -v apt-get >/dev/null 2>&1 || die "This script requires apt-get (Ubuntu/Debian)."
 
-PACKAGES=(
+# ---------------------------------------------------------------------------
+# xPack riscv-none-elf-gcc
+# Cross-platform multilib toolchain (Linux/macOS/Windows).
+# Includes rv32imc/ilp32 (soft-float) libgcc — required for CV32E40P.
+# See: https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack
+# ---------------------------------------------------------------------------
+XPACK_VERSION="15.2.0-1"
+XPACK_TARBALL="xpack-riscv-none-elf-gcc-${XPACK_VERSION}-linux-x64.tar.gz"
+XPACK_URL="https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack/releases/download/v${XPACK_VERSION}/${XPACK_TARBALL}"
+XPACK_INSTALL_DIR="/opt/xpack-riscv-none-elf-gcc-${XPACK_VERSION}"
+XPACK_BIN="${XPACK_INSTALL_DIR}/bin"
+
+APT_PACKAGES=(
     cmake
     ninja-build
-    gcc-riscv64-unknown-elf
-    binutils-riscv64-unknown-elf
     gdb-multiarch
     openocd
     usbutils
@@ -42,12 +52,27 @@ PACKAGES=(
 info "Updating package lists ..."
 sudo apt-get update -qq
 
-info "Installing: ${PACKAGES[*]}"
-sudo apt-get install -y "${PACKAGES[@]}"
+info "Installing apt packages: ${APT_PACKAGES[*]}"
+sudo apt-get install -y "${APT_PACKAGES[@]}"
 
+if [ -x "${XPACK_BIN}/riscv-none-elf-gcc" ]; then
+    info "xPack riscv-none-elf-gcc ${XPACK_VERSION} already installed at ${XPACK_INSTALL_DIR}"
+else
+    info "Downloading xPack riscv-none-elf-gcc ${XPACK_VERSION} ..."
+    wget --no-verbose "${XPACK_URL}" -O "/tmp/${XPACK_TARBALL}"
+    sudo mkdir -p "${XPACK_INSTALL_DIR}"
+    sudo tar xzf "/tmp/${XPACK_TARBALL}" -C /opt
+    rm "/tmp/${XPACK_TARBALL}"
+    info "Installed to ${XPACK_INSTALL_DIR}"
+fi
+
+info ""
+info "Add the toolchain to your PATH:"
+info "  export PATH=${XPACK_BIN}:\$PATH"
 info ""
 info "All dependencies installed."
 info ""
 info "Next steps:"
 info "  1. Run scripts/setup_opella.sh to configure udev rules for the Ashling Opella LD."
 info "  2. (WSL only) Follow the usbipd-win instructions printed by setup_opella.sh."
+