How to build for target x86_64-unknown-linux-none?

help
1

I'm trying to build a project for x86_64-unknown-linux-none, but I get this error:

error[E0463]: can't find crate for `std`
  |
  = note: the `x86_64-unknown-linux-none` target may not be installed
  = help: consider downloading the target with `rustup target add x86_64-unknown-linux-none`

So I started following the compiler instructions to no avail:

~/Projekte/rcon-rs> rustup target add x86_64-unknown-linux-none
error: toolchain 'stable-x86_64-unknown-linux-gnu' does not support target 'x86_64-unknown-linux-none'; did you mean 'x86_64-unknown-linux-gnu'?
note: you can see a list of supported targets with `rustc --print=target-list`
note: if you are adding support for a new target to rustc itself, see https://rustc-dev-guide.rust-lang.org/building/new-target.html
~/Projekte/rcon-rs>              
~/Projekte/rcon-rs> rustup target add x86_64-unknown-linux-none -- --force-non-host
error: toolchain 'stable-x86_64-unknown-linux-gnu' does not support target 'x86_64-unknown-linux-none'; did you mean 'x86_64-unknown-linux-gnu'?
note: you can see a list of supported targets with `rustc --print=target-list`
note: if you are adding support for a new target to rustc itself, see https://rustc-dev-guide.rust-lang.org/building/new-target.html
~/Projekte/rcon-rs> rustup toolchain install stable-x86_64-unknown-linux-none 
error: toolchain 'stable-x86_64-unknown-linux-none' may not be able to run on this system
note: to build software for that platform, try `rustup target add x86_64-unknown-linux-none` instead
note: add the `--force-non-host` flag to install the toolchain anyway
~/Projekte/rcon-rs> rustup toolchain install stable-x86_64-unknown-linux-none --force-non-host
info: syncing channel updates for 'stable-x86_64-unknown-linux-none'
info: latest update on 2025-04-03, rust version 1.86.0 (05f9846f8 2025-03-31)
error: target 'x86_64-unknown-linux-none' not found in channel.  Perhaps check https://doc.rust-lang.org/nightly/rustc/platform-support.html for available targets
~/Projekte/rcon-rs> rustc --print=target-list | grep x86_64-unknown-linux-none 
x86_64-unknown-linux-none
~/Projekte/rcon-rs>

What am I missing here?

2

Which rustc version do you have installed? rustc -vV

Edit: Never mind. You were looking for x86_64-unknown-linux-none, not x86_64-unknown-none. x86_64-unknown-linux-none is a tier 3 target. This means that there are no precompiled versions of it's standard library available. Instead you have to use nightly and build with cargo build -Zbuild-std --target x86_64-unknown-linux-none to have cargo build the standard library for you.

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3

From the target documentation for x86_64-unknown-linux-none:

This target has no support for host tools, std, or alloc.

You can’t install it through rustup since it doesn’t have precompiled artifacts:

Rust does not yet ship pre-compiled artifacts for this target. To compile for this target, you will need to … build your own copy of core by using build-std or similar.

You need to use #![no_std] and use -Z build-std=core. If you want to use std, you need a libc.

1 Like
4

Is there a config option for that in .cargo/config.toml?
I tried to throw it into the rustflags array to no avail:

~/helloworld> cat .cargo/config.toml
[build]
build-stage = 1
target = ["x86_64-unknown-linux-none"]
#rustflags = ["-Zbuild-std"]
~/helloworld> cargo +nightly build -Zbuild-std
warning: unused config key `build.build-stage` in `/home/rne/helloworld/.cargo/config.toml`
   Compiling helloworld v0.1.0 (/home/rne/helloworld)
error[E0463]: can't find crate for `std`
  |
  = note: the `x86_64-unknown-linux-none` target may not support the standard library
  = note: `std` is required by `helloworld` because it does not declare `#![no_std]`
  = help: consider building the standard library from source with `cargo build -Zbuild-std`

error: `#[panic_handler]` function required, but not found

For more information about this error, try `rustc --explain E0463`.
error: could not compile `helloworld` (bin "helloworld") due to 2 previous errors

~/helloworld> cat .cargo/config.toml
[build]
build-stage = 1
target = ["x86_64-unknown-linux-none"]
rustflags = ["-Zbuild-std"]
~/helloworld> cargo +nightly build 
warning: unused config key `build.build-stage` in `/home/rne/helloworld/.cargo/config.toml`
error: failed to run `rustc` to learn about target-specific information

Caused by:
  process didn't exit successfully: `/home/rne/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/rustc - --crate-name ___ --print=file-names -Zbuild-std --target x86_64-unknown-linux-none --crate-type bin --crate-type rlib --crate-type dylib --crate-type cdylib --crate-type staticlib --crate-type proc-macro --print=sysroot --print=split-debuginfo --print=crate-name --print=cfg -Wwarnings` (exit status: 1)
  --- stderr
  error: unknown unstable option: `build-std`

~/helloworld>
5

Adding

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

to .cargo/config.toml works I believe. Adding it to rustflags doesn't work as it is a cargo flag, not a rustc flag.

1 Like