build on nightly, enable linker relaxation and WCH compressed opcodes (#35)

* build everything on nightly

* enable linker relaxation, and WCH compressed opcodes on QingKe V2

Author: aq1018

.github/workflows/ci.yml

@@ -17,13 +17,13 @@ jobs:
         working-directory: lib
     steps:
       - uses: actions/checkout@v6
-      - run: rustup toolchain install stable --profile minimal --component rustfmt,clippy
-      - run: cargo fmt --all -- --check
-      - run: cargo clippy --all-targets -- -D warnings
-      - run: cargo build
-      - run: cargo test
-      - run: cargo doc --no-deps
-      - run: cargo build --release
+      - run: rustup toolchain install nightly --profile minimal --component rustfmt,clippy
+      - run: cargo +nightly fmt --all -- --check
+      - run: cargo +nightly clippy --all-targets -- -D warnings
+      - run: cargo +nightly build
+      - run: cargo +nightly test
+      - run: cargo +nightly doc --no-deps
+      - run: cargo +nightly build --release
 
   cli:
     name: CLI
@@ -34,11 +34,11 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - run: sudo apt-get update && sudo apt-get install -y libudev-dev
-      - run: rustup toolchain install stable --profile minimal --component rustfmt,clippy
-      - run: cargo fmt --all -- --check
-      - run: cargo clippy -- -D warnings
-      - run: cargo build
-      - run: cargo build --release
+      - run: rustup toolchain install nightly --profile minimal --component rustfmt,clippy
+      - run: cargo +nightly fmt --all -- --check
+      - run: cargo +nightly clippy -- -D warnings
+      - run: cargo +nightly build
+      - run: cargo +nightly build --release
 
   ch32-v003:
     name: CH32V003 (${{ matrix.chip }})
@@ -135,29 +135,28 @@ jobs:
       - uses: actions/checkout@v6
       - name: Install toolchain
         run: |
-          rustup toolchain install stable --profile minimal --component rustfmt,clippy
-          rustup target add riscv32imc-unknown-none-elf
+          rustup toolchain install nightly --profile minimal --component rustfmt,clippy --target riscv32imc-unknown-none-elf
       - name: Clippy libraries
-        run: cd ch32 && cargo clippy --no-default-features --features ${{ matrix.chip }} --target riscv32imc-unknown-none-elf -- -D warnings
+        run: cd ch32 && cargo +nightly clippy --no-default-features --features ${{ matrix.chip }} --target riscv32imc-unknown-none-elf -- -D warnings
       - name: Build libraries
-        run: cd ch32 && cargo build --no-default-features --features ${{ matrix.chip }} --target riscv32imc-unknown-none-elf --release
+        run: cd ch32 && cargo +nightly build --no-default-features --features ${{ matrix.chip }} --target riscv32imc-unknown-none-elf --release
       - name: Clippy libraries (half-duplex)
-        run: cd ch32 && cargo clippy --no-default-features --features ${{ matrix.chip }},half-duplex --target riscv32imc-unknown-none-elf -- -D warnings
+        run: cd ch32 && cargo +nightly clippy --no-default-features --features ${{ matrix.chip }},half-duplex --target riscv32imc-unknown-none-elf -- -D warnings
       - name: Fmt examples
-        run: cd examples/ch32/v103 && cargo fmt --all -- --check
+        run: cd examples/ch32/v103 && cargo +nightly fmt --all -- --check
       - name: Clippy boot (system-flash)
-        run: cd examples/ch32/v103 && cargo clippy -p boot --no-default-features --features "${{ matrix.chip }},system-flash" -- -D warnings
+        run: cd examples/ch32/v103 && cargo +nightly clippy -p boot --no-default-features --features "${{ matrix.chip }},system-flash" -- -D warnings
       - name: Build boot (system-flash)
-        run: cd examples/ch32/v103 && cargo build -p boot --no-default-features --features "${{ matrix.chip }},system-flash" --release
+        run: cd examples/ch32/v103 && cargo +nightly build -p boot --no-default-features --features "${{ matrix.chip }},system-flash" --release
       - name: Clippy boot (user-flash)
-        run: cd examples/ch32/v103 && cargo clippy -p boot --no-default-features --features "${{ matrix.chip }},user-flash" -- -D warnings
+        run: cd examples/ch32/v103 && cargo +nightly clippy -p boot --no-default-features --features "${{ matrix.chip }},user-flash" -- -D warnings
       - name: Build boot (user-flash)
-        run: cd examples/ch32/v103 && cargo build -p boot --no-default-features --features "${{ matrix.chip }},user-flash" --release
+        run: cd examples/ch32/v103 && cargo +nightly build -p boot --no-default-features --features "${{ matrix.chip }},user-flash" --release
       - name: Clippy app (system-flash)
-        run: cd examples/ch32/v103 && cargo clippy -p app --no-default-features --features "${{ matrix.chip }},system-flash" -- -D warnings
+        run: cd examples/ch32/v103 && cargo +nightly clippy -p app --no-default-features --features "${{ matrix.chip }},system-flash" -- -D warnings
       - name: Build app (system-flash)
-        run: cd examples/ch32/v103 && cargo build -p app --no-default-features --features "${{ matrix.chip }},system-flash" --release
+        run: cd examples/ch32/v103 && cargo +nightly build -p app --no-default-features --features "${{ matrix.chip }},system-flash" --release
       - name: Clippy app (user-flash)
-        run: cd examples/ch32/v103 && cargo clippy -p app --no-default-features --features "${{ matrix.chip }},user-flash" -- -D warnings
+        run: cd examples/ch32/v103 && cargo +nightly clippy -p app --no-default-features --features "${{ matrix.chip }},user-flash" -- -D warnings
       - name: Build app (user-flash)
-        run: cd examples/ch32/v103 && cargo build -p app --no-default-features --features "${{ matrix.chip }},user-flash" --release
+        run: cd examples/ch32/v103 && cargo +nightly build -p app --no-default-features --features "${{ matrix.chip }},user-flash" --release

docs/contributing.md

@@ -37,10 +37,9 @@ Each directory is its own Cargo workspace with an independent `Cargo.lock`. A "c
 
 ## Rust toolchain
 
-- **Library crates (`lib/`, `cli/`)** — stable Rust 1.85+, edition 2024.
-- **CH32 example binaries** — nightly, for `-Zbuild-std` on `riscv32ec-unknown-none-elf` (V003 / V00x) or the stable `riscv32imc-unknown-none-elf` target (V103).
+Everything builds and is tested on nightly, edition 2024: the library crates (`lib/`, `cli/`, `ch32/`) and the CH32 examples. The V003 / V00x examples need it for `-Zbuild-std` on `riscv32ec-unknown-none-elf`; the V103 examples use the built-in `riscv32imc-unknown-none-elf` target with linker relaxation (`+relax`), which stable rustc warns about as an unstable target feature.
 
-Each example workspace pins its toolchain via `rust-toolchain.toml`.
+The repository root and each example workspace pin nightly via `rust-toolchain.toml`.
 
 ## Running tests
 

docs/design.md

@@ -23,6 +23,7 @@ To build your bootloader, you create a small crate with a `main.rs` that wires u
 
 Beyond the usual Cargo profile tricks (`opt-level = "z"`, LTO, `codegen-units = 1`, `panic = "abort"`), fitting a real bootloader in 1920 bytes required more deliberate choices:
 
+- **Linker relaxation and WCH compressed opcodes** - the examples enable `+relax`, so the linker shrinks every `auipc`+`jalr` call pair to `jal` or `c.jal`, and on QingKe V2 cores (V003, V00x) `+xwchc`, WCH's 16-bit byte and halfword loads and stores. Together they take the V003 bootloader from 1898 to 1710 bytes. QingKe V3A (V103) has no XW extension, so its example enables only `+relax`.
 - **No HAL crates** — bare metal register access via PAC crates only; HAL abstractions are too expensive for this budget.
 - **Custom runtime** — `tinyboot-ch32-rt` replaces `qingke-rt` in the bootloader; its startup is just GP/SP init and a jump to main (20 bytes of assembly instead of ~1.4KB of full runtime).
 - **Symmetric frame format** — the same `Frame` struct is used for both requests and responses with one shared parse and format path, eliminating code duplication.

docs/getting-started.md

@@ -24,7 +24,7 @@ cargo install wlink
 cargo install tinyboot
 ```
 
-The CH32V003 examples use `riscv32ec-unknown-none-elf`, which is a Tier 3 target that `-Zbuild-std` builds on the fly — nightly is required. CH32V103 examples use the stable `riscv32imc-unknown-none-elf` target.
+The CH32V003 examples use `riscv32ec-unknown-none-elf`, which is a Tier 3 target that `-Zbuild-std` builds on the fly — nightly is required. CH32V103 examples use the built-in `riscv32imc-unknown-none-elf` target, also on nightly like every tinyboot build.
 
 ## 2. Clone the repo
 

docs/porting-series.md

@@ -188,7 +188,7 @@ Then flash to hardware using `wlink` and walk through the [standard test sequenc
 
 Add the new series to `.github/workflows/ci.yml`. Each series has its own job with a matrix of variants. The CI runs `cargo fmt`, `cargo clippy`, and `cargo build --release` for both `system-flash` and `user-flash` modes on every variant. This ensures formatting, lint, compilation, and that the bootloader fits within the system flash region.
 
-Add a new job following the pattern of the existing series jobs. Use the V003 job as a template for custom-target chips (nightly + `-Zbuild-std`) or the V103 job for standard-target chips (stable + `rustup target add`).
+Add a new job following the pattern of the existing series jobs. Use the V003 job as a template for custom-target chips (nightly + `-Zbuild-std`) or the V103 job for standard-target chips (nightly with the target added).
 
 ```yaml
 strategy:

examples/ch32/v003/riscv32ec-unknown-none-elf.json

@@ -6,7 +6,7 @@
   "data-layout": "e-m:e-p:32:32-i64:64-n32-S32",
   "eh-frame-header": false,
   "emit-debug-gdb-scripts": false,
-  "features": "+e,+c,+forced-atomics",
+  "features": "+e,+c,+forced-atomics,+xwchc,+relax",
   "linker": "rust-lld",
   "linker-flavor": "gnu-lld",
   "llvm-target": "riscv32",

examples/ch32/v00x/riscv32ec-unknown-none-elf.json

@@ -6,7 +6,7 @@
   "data-layout": "e-m:e-p:32:32-i64:64-n32-S32",
   "eh-frame-header": false,
   "emit-debug-gdb-scripts": false,
-  "features": "+e,+c,+forced-atomics",
+  "features": "+e,+c,+forced-atomics,+xwchc,+relax",
   "linker": "rust-lld",
   "linker-flavor": "gnu-lld",
   "llvm-target": "riscv32",

examples/ch32/v103/.cargo/config.toml

@@ -5,6 +5,8 @@ target = "riscv32imc-unknown-none-elf"
 rustflags = [
   "-C", "link-arg=-Tlink.x",
   "-C", "link-arg=--nmagic",
+  # Linker relaxation: calls shrink from auipc+jalr to jal/c.jal.
+  "-C", "target-feature=+relax",
 ]
 runner = "probe-rs run --chip CH32V103"
 

examples/ch32/v103/app/src/main.rs

@@ -73,11 +73,13 @@ fn main() -> ! {
     // system-flash: pass BOOT0 pin, the level that selects system flash,
     // and the reset delay in cycles (RC ~1ms @ 8MHz = 8000; flip-flop: 0).
     let mut app = tinyboot_ch32::app::new_app(core::cfg_select! {
-        feature = "system-flash" => tinyboot_ch32::app::BootCtl::new(
-            tinyboot_ch32::app::Pin::PB1,
-            tinyboot_ch32::app::Level::High,
-            8000,
-        ),
+        feature = "system-flash" => {
+            tinyboot_ch32::app::BootCtl::new(
+                tinyboot_ch32::app::Pin::PB1,
+                tinyboot_ch32::app::Level::High,
+                8000,
+            )
+        }
         _ => tinyboot_ch32::app::BootCtl::new(),
     });
 

examples/ch32/v103/rust-toolchain.toml

@@ -0,0 +1,4 @@
+[toolchain]
+channel = "nightly"
+components = ["rustfmt", "clippy", "rust-analyzer"]
+targets = ["riscv32imc-unknown-none-elf"]