Summary:
- Added support for `panic_immediate_abort` in Rust builds, which causes the system to abort immediately on panic instead of unwinding the stack
- Enabled `-Zbuild-std-features=panic_immediate_abort` flag for release builds when `CONFIG_DEBUG_FULLOPT` is set
- Updated both CMake and Makefile build systems to include the new flag
Impact:
- Significantly reduces binary size (e.g., from 2270605 to 84987 bytes for riscv64imc)
- Changes panic behavior to immediate abort, which may be preferred for embedded systems
- Improves system reliability by preventing undefined behavior from stack unwinding in constrained environments
- Maintains compatibility with existing Rust code while providing a more deterministic panic handling mechanism
For example, if it is enabled, the system will panic immediately:
```
NuttShell (NSH) NuttX-12.8.0
nsh> hello_rust_cargo
{"name":"John","age":30}
{"name":"Jane","age":25}
Deserialized: Alice is 28 years old
Pretty JSON:
{
"name": "Alice",
"age": 28
}
riscv_exception: EXCEPTION: Illegal instruction. MCAUSE: 0000000000000002, EPC: 0000000080027df6, MTVAL: 0000000000000000
riscv_exception: PANIC!!! Exception = 0000000000000002
dump_assert_info: Current Version: NuttX 12.8.0 8e3621e059 Jan 20 2025 14:45:00 risc-v
dump_assert_info: Assertion failed panic: at file: :0 task: hello_rust_cargo process: hello_rust_cargo 0x80020588
/* Stack dump from NuttX */
```
vs the default behavior:
```
NuttShell (NSH) NuttX-12.8.0
nsh> hello_rust_cargo
{"name":"John","age":30}
{"name":"Jane","age":25}
Deserialized: Alice is 28 years old
Pretty JSON:
{
"name": "Alice",
"age": 28
}
thread '<unnamed>' panicked at /home/huang/Work/rust/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/src/rust/library/std/src/sys/random/unix_legacy.rs:19:10:
failed to generate random data: Os { code: 2, kind: NotFound, message: "No such file or directory" }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
nsh>
```
Signed-off-by: Huang Qi <huangqi3@xiaomi.com>
Build Rust applictions with cargo is the most commn way,
and it's more easy to cooporate with Rust ecosystem.
This example shows how to use cargo to build a simple hello world
application.
And please notice that you need to install nighly version of rustc
to support this feature, any version after https://github.com/rust-lang/rust/pull/127755
is merged, can use NuttX as cargo target directly.
Build
-----
To build hello_rust_cargo application, you can use any target that based
on RISCV32IMAC, for example:
```
cmake -B build -DBOARD_CONFIG=rv-virt:nsh -GNinja .
```
And disable ARCH_FPU in menuconfig, since the hard coded target triple
in this demo is `riscv32imac`.
Signed-off-by: Huang Qi <huangqi3@xiaomi.com>
