Building on Arm M4 Pro uses x86_64 toolchain binaries within docker (slow builds)

[vlovich]

Checklist

• I've looked through the issues and pull requests for similar reports

Describe your issue

I'm trying to compile for raspberry pi on MacOS (via colima). This may be the same as #1716 but I'm not sure.

I had a problem where the docker image wouldn't run

Details

``` % cross build [+] Building 3.3s (2/2) FINISHED docker:colima => [internal] load build definition from Dockerfile.aarch64-unknown-linux-gnu-custom 0.0s => => transferring dockerfile: 248B 0.0s => ERROR [internal] load metadata for ghcr.io/cross-rs/aarch64-unknown-linux-gnu:0.2.5 3.2s ------ > [internal] load metadata for ghcr.io/cross-rs/aarch64-unknown-linux-gnu:0.2.5: ------ Dockerfile.aarch64-unknown-linux-gnu-custom:2 -------------------- 1 | 2 | >>> FROM ghcr.io/cross-rs/aarch64-unknown-linux-gnu:0.2.5 3 | ARG CROSS_DEB_ARCH= 4 | ARG CROSS_CMD -------------------- ERROR: failed to build: failed to solve: ghcr.io/cross-rs/aarch64-unknown-linux-gnu:0.2.5: failed to resolve source metadata for ghcr.io/cross-rs/aarch64-unknown-linux-gnu:0.2.5: no match for platform in manifest: not found Error: 0: could not run container 1: when building custom image 2: when pre-building 3: `docker build --label 'org.cross-rs.for-cross-target=aarch64-unknown-linux-gnu' --label 'org.cross-rs.workspace_root=/Users/me/projects/my-workspace' --tag cross-custom-device:aarch64-unknown-linux-gnu-ac370-pre-build --build-arg 'CROSS_CMD=apt-get update apt-get --assume-yes install capnproto' --build-arg 'CROSS_DEB_ARCH=arm64' --file /Users/me/projects/my-workspace/my-crate/target/aarch64-unknown-linux-gnu/Dockerfile.aarch64-unknown-linux-gnu-custom /Users/me/my-workspace/sky-ai/my-crate` failed with exit status: 1 ```

until I used the main branch as recommended in that issue.

However, when I reinstalled from main, while the build is running, it's still building very slowly because it's using the x86-64 rust toolchain which requires emulation:

docker exec -it f47a9ae7688d bash
I have no name!@f47a9ae7688d:/Users/me/projects/my-workspace/my-crate$ ps aux | grep cargo 
502            1  0.0  0.3 147132  7720 pts/0    Ssl+ 22:09   0:00 /usr/bin/qemu-x86_64 /usr/bin/sh sh -c PATH="$PATH":"/Users/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin" cargo build --target aarch64-unknown-linux-gnu
502            8  0.7  6.9 534800 139784 pts/0   Sl+  22:09   0:01 /usr/bin/qemu-x86_64 /Users/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo cargo build --target aarch64-unknown-linux-gnu
502          261  0.0  5.7 534800 115660 pts/0   Sl+  22:10   0:00 /usr/bin/qemu-x86_64 /Users/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo cargo build --target aarch64-unknown-linux-gnu
502         1030 71.0  9.6 629824 192684 pts/0   Sl+  22:12   0:00 /usr/bin/qemu-x86_64 /Users/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/rustc rustc --crate-name errno --edition=2018 /Users/me/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/errno-0.3.14/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --diagnostic-width=250 --crate-type lib --emit=dep-info,metadata,link -C embed-bitcode=no -C debuginfo=2 -C split-debuginfo=unpacked --warn=unexpected_cfgs --check-cfg cfg(target_os, values("cygwin")) --cfg feature="default" --cfg feature="std" --check-cfg cfg(docsrs,test) --check-cfg cfg(feature, values("default", "std")) -C metadata=5d57d3d22ae1413d -C extra-filename=-6d579b2674dba8ef --out-dir /target/aarch64-unknown-linux-gnu/debug/deps --target aarch64-unknown-linux-gnu -C linker=aarch64-linux-gnu-gcc -L dependency=/target/aarch64-unknown-linux-gnu/debug/deps -L dependency=/target/debug/deps --extern libc=/target/aarch64-unknown-linux-gnu/debug/deps/liblibc-e2d118a350217de9.rmeta --cap-lints allow
502         1038  0.0  0.4 147932  8236 pts/1    Sl+  22:12   0:00 /usr/bin/qemu-x86_64 /usr/bin/grep grep cargo
I have no name!@f47a9ae7688d:/Users/me/projects/my-workspace/my-crate$ file  /Users/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo
/Users/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, with debug_info, not stripped

Here's my Cross.toml

[build]
default-target = "aarch64-unknown-linux-gnu"

I couldn't find an issue matching this exactly.

What target(s) are you cross-compiling for?

aarch64-unknown-linux-gnu

Which operating system is the host (e.g computer cross is on) running?

• macOS
• Windows
• Linux / BSD
• other OS (specify in description)

What architecture is the host?

• x86_64 / AMD64
• arm32
• arm64 (including Mac M1)

What container engine is cross using?

• docker
• podman
• other container engine (specify in description)

cross version

cross 0.2.5 (426e811 2026-01-03)

Example

No response

Additional information / notes

No response

[Emilgardis]

we don't currently publish images that would work with arm64, see #751 for that.

[vlovich]

Sweet - thanks for linking the issue. For some reason my spelunking didn't locate it.