Rust Apps for Apache NuttX RTOS: Build NuttX for QEMU. See https://github.com/lupyuen/nuttx-rust-app

build-nuttx-qemu.log

$ mkdir nuttx
$ cd nuttx
$ git clone https://github.com/apache/nuttx nuttx
$ git clone https://github.com/apache/nuttx-apps apps
$ cd nuttx

$ tools/configure.sh rv-virt:nsh64
$ make menuconfig
## TODO: Enable "Hello Rust" Example App
## https://github.com/lupyuen2/wip-nuttx/blob/rust/boards/risc-v/qemu-rv/rv-virt/configs/nsh64/defconfig

## Build NuttX with Tracing Enabled
$ make --trace

## Compile "hello_main.c" with GCC Compiler
riscv64-unknown-elf-gcc \
  -march=rv64imafdc \
  -mabi=lp64d \
  -c \
  -fno-common \
  -Wall \
  -Wstrict-prototypes \
  -Wshadow \
  -Wundef \
  -Wno-attributes \
  -Wno-unknown-pragmas \
  -Wno-psabi \
  -Os \
  -fno-strict-aliasing \
  -fomit-frame-pointer \
  -ffunction-sections \
  -fdata-sections \
  -g \
  -mcmodel=medany \
  -isystem /Users/Luppy/riscv/nuttx/include \
  -D__NuttX__ \
  -DNDEBUG  \
  -pipe \
  -I "/Users/Luppy/riscv/apps/include" \
  -Dmain=hello_main  hello_main.c \
  -o  hello_main.c.Users.Luppy.riscv.apps.examples.hello.o

## Compile "hello_rust_main.rs" with Rust Compiler
rustc \
  --target riscv64i-unknown-none-elf \
  --edition 2021 \
  --emit obj \
  -g \
  -C panic=abort \
  -O \
  hello_rust_main.rs \
  -o hello_rust_main.rs.Users.Luppy.riscv.apps.examples.hello_rust.o

error: Error loading target specification: Could not find specification for target "riscv64i-unknown-none-elf". Run `rustc --print target-list` for a list of built-in targets

make[2]: *** [/Users/Luppy/riscv/apps/Application.mk:275: hello_rust_main.rs.Users.Luppy.riscv.apps.examples.hello_rust.o] Error 1
make[1]: *** [Makefile:51: /Users/Luppy/riscv/apps/examples/hello_rust_all] Error 2
make: *** [tools/LibTargets.mk:232: /Users/Luppy/riscv/apps/libapps.a] Error 2

$ rustup target add riscv64gc-unknown-none-elf
$ pushd ../apps/examples/hello_rust 
$ rustc \
  --target riscv64gc-unknown-none-elf \
  --edition 2021 \
  --emit obj \
  -g \
  -C panic=abort \
  -O \
  hello_rust_main.rs \
  -o hello_rust_main.rs.Users.Luppy.riscv.apps.examples.hello_rust.o
$ popd
$ make