add details for csky-unknown-linux-gnuabiv2 and add docs

3 files changed, 66 insertions, 13 deletions

diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
index a78b5314fcc..371ee378d1a 100644
--- a/src/doc/rustc/src/platform-support.md
+++ b/src/doc/rustc/src/platform-support.md
@@ -259,7 +259,7 @@ target | std | host | notes
 `avr-unknown-gnu-atmega328` | * |  | AVR. Requires `-Z build-std=core`
 `bpfeb-unknown-none` | * |  | BPF (big endian)
 `bpfel-unknown-none` | * |  | BPF (little endian)
-`csky-unknown-linux-gnuabiv2` | ? |  | C-SKY iv2 Linux
+`csky-unknown-linux-gnuabiv2` | ✓ |  | C-SKY abiv2 Linux(little endian)
 `hexagon-unknown-linux-musl` | ? |  |
 `i386-apple-ios` | ✓ |  | 32-bit x86 iOS
 [`i586-pc-nto-qnx700`](platform-support/nto-qnx.md) | * |  | 32-bit x86 QNX Neutrino 7.0 RTOS |
diff --git a/src/doc/rustc/src/platform-support/csky-unknown-linux-gnuabiv2.md b/src/doc/rustc/src/platform-support/csky-unknown-linux-gnuabiv2.md
index 240d58596cf..e73598be0d9 100644
--- a/src/doc/rustc/src/platform-support/csky-unknown-linux-gnuabiv2.md
+++ b/src/doc/rustc/src/platform-support/csky-unknown-linux-gnuabiv2.md
@@ -5,6 +5,8 @@
 This target supports [C-SKY](https://github.com/c-sky) CPUs with `abi` v2 and `glibc`.
 
 https://c-sky.github.io/
+https://gitlab.com/c-sky/
+
 ## Target maintainers
 
 * [@Dirreke](https://github.com/Dirreke)
@@ -14,20 +16,55 @@ https://c-sky.github.io/
 
 ## Building the target
 
-add `csky-unknown-linux-gnuabiv2` to the `target` list in `config.toml` and `./x build`.
+### 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](https://occ-oss-prod.oss-cn-hangzhou.aliyuncs.com/resource/1356021/1619528643136/csky-linux-gnuabiv2-tools-x86_64-glibc-linux-4.9.56-20210423.tar.gz), 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`:
+
+```toml
+[build]
+target = ["x86_64-unknown-linux-gnu", "csky-unknown-linux-gnuabiv2"]
+stage = 2
 
-## Building Rust programs
+[target.csky-unknown-linux-gnuabiv2]
+# ADJUST THIS PATH TO POINT AT YOUR TOOLCHAIN
+cc = "${TOOLCHAIN_PATH}/bin/csky-linux-gnuabiv2-gcc"
 
-Rust programs can be built for that target:
+### Build
 
-```text
-cargo +stage2 --target csky-unknown-linux-gnuabiv2 your-code.rs
+```sh
+# in rust dir
+./x.py build --stage 2
 ```
 
-## Testing
+## Building and Running Rust programs
 
-Currently there is no support to run the rustc test suite for this target.
+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!
 
-## Cross-compilation toolchains and C code
+To use:
+
+* Install `qemu-cskyv2` (If you don't already have a qemu, you can download from [here](https://occ-oss-prod.oss-cn-hangzhou.aliyuncs.com/resource//1689324918932/xuantie-qemu-x86_64-Ubuntu-18.04-20230714-0202.tar.gz"), and unpack it into a directory.)
+* Link your built toolchain via:
+  * `rustup toolchain link stage2 ${RUST}/build/x86_64-unknown-linux-gnu/stage2`
+* Create a test program
+
+```sh
+cargo new hello_world
+cd hello_world
+```
+
+* Build and run
+
+```sh
+CARGO_TARGET_CSKY_UNKNOWN_LINUX_GNUABIV2_RUNNER=${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-features=+crt-static" \
+cargo +stage2 run --target csky-unknown-linux-gnuabiv2
+```
 
-This target can be cross-compiled from `x86_64` on either Linux systems with [`csky-linux-gunabiv2-tools-x86_64-glibc-linux`](https://github.com/c-sky/toolchain-build).
+Attention: The dynamic-linked program may nor be run by `qemu-cskyv2` but can be run on the target.
diff --git a/src/doc/unstable-book/src/language-features/asm-experimental-arch.md b/src/doc/unstable-book/src/language-features/asm-experimental-arch.md
index d52287051c6..968c9bb4ebb 100644
--- a/src/doc/unstable-book/src/language-features/asm-experimental-arch.md
+++ b/src/doc/unstable-book/src/language-features/asm-experimental-arch.md
@@ -82,8 +82,8 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
 | MSP430       | `reg`                           | None           | `i8`, `i16`                             |
 | M68k         | `reg`, `reg_addr`               | None           | `i16`, `i32`                            |
 | M68k         | `reg_data`                      | None           | `i8`, `i16`, `i32`                      |
-| CSKY         | `reg`                           | None           | `i8`, `i16`, `i32`, `i64`               |
-| CSKY         | `freg`                          | None           | `f32`, `f64`                            |
+| CSKY         | `reg`                           | None           | `i8`, `i16`, `i32`                      |
+| CSKY         | `freg`                          | None           | `f32`,                                  |
 | s390x        | `reg`                           | None           | `i8`, `i16`, `i32`, `i64`               |
 | s390x        | `freg`                          | None           | `f32`, `f64`                            |
 
@@ -107,9 +107,16 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
 | M68k         | `a5`          | `bp`      |
 | M68k         | `a6`          | `fp`      |
 | M68k         | `a7`          | `sp`, `usp`, `ssp`, `isp` |
+| CSKY         | `r[0-3]`      | `a[0-3]`  |
+| CSKY         | `r[4-11]`     | `l[0-7]`  |
+| CSKY         | `r[12-13]`    | `t[0-1]`  |
 | CSKY         | `r14`         | `sp`      |
 | CSKY         | `r15`         | `lr`      |
-| CSKY         | `r28`         | `gb`, `rgb`, `rdb` |
+| CSKY         | `r[16-17]`    | `l[8-9]`  |
+| CSKY         | `r[18-25]`    | `t[2-9]`  |
+| CSKY         | `r28`         | `rgb`     |
+| CSKY         | `r29`         | `rtb`     |
+| CSKY         | `r30`         | `svbr`    |
 | CSKY         | `r31`         | `tls`     |
 
 > **Notes**:
@@ -132,6 +139,13 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
 | AVR          | `r0`, `r1`, `r1r0`                      | Due to an issue in LLVM, the `r0` and `r1` registers cannot be used as inputs or outputs.  If modified, they must be restored to their original values before the end of the block. |
 |MSP430        | `r0`, `r2`, `r3`                        | These are the program counter, status register, and constant generator respectively. Neither the status register nor constant generator can be written to.                          |
 | M68k         | `a4`, `a5`                              | Used internally by LLVM for the base pointer and global base pointer. |
+| CSKY         | `r7`, `r28`                             | Used internally by LLVM for the base pointer and global base pointer. |
+| CSKY         | `r8`                                    | Used internally by LLVM for the frame pointer. |
+| CSKY         | `r14`                                   | Used internally by LLVM for the stack pointer. |
+| CSKY         | `r15`                                   | This is the link register. |
+| CSKY         | `r[26-30]`                              | Reserved by its ABI.       |
+| CSKY         | `r31`                                   | This is the TLS register.  |
+
 
 ## Template modifiers
 
@@ -148,6 +162,8 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
 | PowerPC      | `freg`         | None     | `0`            | None          |
 | s390x        | `reg`          | None     | `%r0`          | None          |
 | s390x        | `freg`         | None     | `%f0`          | None          |
+| CSKY         | `reg`          | None     | `r0`           | None          |
+| CSKY         | `freg`         | None     | `f0`           | None          |
 
 # Flags covered by `preserves_flags`