# `csky-unknown-linux-gnuabiv2`

Tier: 3

This target supports C-SKY CPUs with `abi` v2 and `glibc`.

target | std | host | notes
--- | --- | --- | ---
`csky-unknown-linux-gnuabiv2` | ✓ |  | C-SKY abiv2 Linux (little endian)
`csky-unknown-linux-gnuabiv2hf` | ✓ |  | C-SKY abiv2 Linux, hardfloat (little endian)

Reference:

- CSKY ABI Manual
- csky-linux-gnuabiv2-toolchain
- csky-linux-gnuabiv2-qemu

other links:

- https://c-sky.github.io/
- https://gitlab.com/c-sky/

## Target maintainers

- @Dirreke

## Requirements

## Building the target

### Get a C toolchain

Compiling rust for this target has been tested on `x86_64` linux hosts. Other host types have not been tested, but may work, if you can find a suitable cross compilation toolchain for them.

If you don't already have a suitable toolchain, you can download from here, and unpack it into a directory.

### Configure rust

The target can be built by enabling it for a `rustc` build, by placing the following in `config.toml`:

    [build]
    target = ["x86_64-unknown-linux-gnu", "csky-unknown-linux-gnuabiv2", "csky-unknown-linux-gnuabiv2hf"]
    stage = 2

    [target.csky-unknown-linux-gnuabiv2]
    # ADJUST THIS PATH TO POINT AT YOUR TOOLCHAIN
    cc = "${TOOLCHAIN_PATH}/bin/csky-linux-gnuabiv2-gcc"

    [target.csky-unknown-linux-gnuabiv2hf]
    # ADJUST THIS PATH TO POINT AT YOUR TOOLCHAIN
    cc = "${TOOLCHAIN_PATH}/bin/csky-linux-gnuabiv2-gcc"

### Build

    # in rust dir
    ./x.py build --stage 2

## Building and Running Rust programs

To test cross-compiled binaries on a `x86_64` system, you can use the `qemu-cskyv2`. This avoids having a full emulated ARM system by doing dynamic binary translation and dynamic system call translation. It lets you run CSKY programs directly on your `x86_64` kernel. It's very convenient!

To use:

- Install `qemu-cskyv2` (If you don't already have a qemu, you can download from here, and unpack it into a directory.)
- Link your built toolchain via:
  - `rustup toolchain link stage2 ${RUST}/build/x86_64-unknown-linux-gnu/stage2`
- Create a test program

    cargo new hello_world
    cd hello_world

- Build and run

    CARGO_TARGET_CSKY_UNKNOWN_LINUX_GNUABIV2_RUNNER=${QEMU_PATH}/bin/qemu-cskyv2 -L ${TOOLCHAIN_PATH}/csky-linux-gnuabiv2/libc \
    CARGO_TARGET_CSKY_UNKNOWN_LINUX_GNUABIV2_LINKER=${TOOLCHAIN_PATH}/bin/csky-linux-gnuabiv2-gcc \
    RUSTFLAGS="-C target-feature=+crt-static" \
    cargo +stage2 run --target csky-unknown-linux-gnuabiv2

Attention: The dynamic-linked program may nor be run by `qemu-cskyv2` but can be run on the target.