I’m on Rust with AVR atmega328p,
using

• nightly-2024-11-12-aarch64-unknown-linux-gnu (default)
• rustc 1.84.0-nightly (81eef2d36 2024-11-11)

I have a global_asm! macro which compiles Ok in a bin main.rs
and gives a compile error in a lib lib.rs

The error is

error: <inline asm>:2:5: instruction requires a CPU feature not currently enabled
    jmp 0
    ^

The macro (the jump-address 0 is for demonstration only, compile fails on jmp instruction, not the address) :

//
global_asm!(r#"
    jmp 0
"#);

To test, I have two crates, one to test as –bin with main.rs, one to test as –lib with lib.rs

Both crates have .cargo/config.toml

[build]
target = "avr-atmega328p.json"

[target.avr-atmega328p]
rustflags = [
    #
    "-Clink-arg=-nostartfiles",
]

[unstable]
build-std = ["core"]

Both have Config.toml

[package]
name = "..."
edition = "2021"

[dependencies]

[profile.release]
panic = "abort"
lto = true

The main.rs in the bin test crate :

//!
#![no_std]
#![no_main]
//
#![allow(unused_imports)]
//
#![feature(asm_experimental_arch)]

use core::arch::{ asm, global_asm };

//
global_asm!(r#"
    jmp 0
"#);

///
use core::panic::PanicInfo;
#[panic_handler]
fn panic(_panic: &PanicInfo<'_>) -> ! {
    loop {
    }
}

… compiles and links fine !

The lib.rs in the lib test crate :

//!
#![no_std]
//
#![allow(unused_imports)]
//
#![feature(asm_experimental_arch)]

use core::arch::{ asm, global_asm };

//
global_asm!(r#"
    jmp 0
"#);

… and gives compile error

error: <inline asm>:2:5: instruction requires a CPU feature not currently enabled
    jmp 0
    ^

Command for both crates is cargo build --release

May be someone has an idea how to use the assembler jmp instruction in a lib.

Btw. using rjmp xxx works, but I need far jumps.

thx