Add aarch64 support by ludfjig · Pull Request #32 · hyperlight-dev/cargo-hyperlight

ludfjig · 2026-03-10T17:44:20Z

Adds support for compiling aarch64, with some fixes for cross compiling from x86_64 as well

canonicalize() resolves the cargo -> rustup symlink, causing commands like 'cargo rustc' to be invoked as 'rustup rustc' which doesn't understand cargo-specific arguments. Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com> Signed-off-by: Lucy Menon <168595099+syntactically@users.noreply.github.com>

User CLI args like --target aarch64-unknown-none were passed through to the final cargo build command, overriding the resolved CARGO_BUILD_TARGET env var set by populate_from_args. Filter these out since the resolved hyperlight target is set via environment variable. Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com> Signed-off-by: Lucy Menon <168595099+syntactically@users.noreply.github.com>

- Add aarch64-hyperlight-none target spec derived from aarch64-unknown-none with hyperlight customizations - Select correct musl arch headers (aarch64 vs x86_64) - Use appropriate clang --target for aarch64 - Make -mno-red-zone x86_64-only (aarch64 has no red zone) - Fix get_spec to pass --target as CLI arg instead of env var Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com> Signed-off-by: Lucy Menon <168595099+syntactically@users.noreply.github.com>

- Add concurrency group to cancel stale CI runs - Gate KVM setup on X64 runners - Gate run-guest on X64 (no host support on ARM yet) - Update README to mention aarch64 target - Use arch() in justfile for target-independent paths Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com> Signed-off-by: Lucy Menon <168595099+syntactically@users.noreply.github.com>

aarch64: improve rust target json: - Set a relocation model that makes it easier for our loader - Compile for Armv8.1-A, since we likely don't care about older machines, and this allows us to use FEAT_LSE. Signed-off-by: Lucy Menon <168595099+syntactically@users.noreply.github.com>

Fix a Rust warning, hopefully fixing CI. Signed-off-by: Lucy Menon <168595099+syntactically@users.noreply.github.com>

syntactically · 2026-05-26T19:11:22Z

@ludfjig I rebased this PR and added some minor fixes used by the main hyperlight PR.

Looks like CI is passing, so hopefully we can merge that soon.

Copilot

Pull request overview

This PR adds support for building Hyperlight guest binaries targeting aarch64-hyperlight-none, and adjusts argument forwarding / toolchain behavior to improve cross-compilation correctness.

Changes:

Add a new aarch64-hyperlight-none Rust target spec derived from aarch64-unknown-none, and update target-spec generation to pass --target explicitly.
Adjust clang/cflags generation to use an aarch64 --target and make -mno-red-zone x86_64-only.
Improve cargo invocation behavior by avoiding canonicalize() on the cargo path and filtering --target / --target-dir from forwarded CLI args; update docs/CI/justfile for multi-arch support.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
`src/toolchain.rs`	Adds aarch64-aware clang target selection and changes libc header preparation logic.
`src/sysroot.rs`	Introduces `aarch64-hyperlight-none` target-spec customization and adjusts how base target specs are queried.
`src/command.rs`	Filters `--target` / `--target-dir` from forwarded args to avoid overriding resolved env-based target settings.
`src/cargo_cmd.rs`	Stops canonicalizing the cargo binary path to avoid resolving rustup symlinks.
`README.md`	Documents default target selection on ARM and updates output path description.
`justfile`	Uses `arch()` to make the guest path target-arch independent.
`.github/workflows/ci.yml`	Adds concurrency cancellation and gates KVM / guest execution based on runner architecture.

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syntactically · 2026-05-28T16:58:57Z

+    if !args.target.starts_with("aarch64") {
+        // Detect which libc variant is present: picolibc or legacy musl
+        let include_dirs: &[&str] = &[
+            // directories for musl
+            "third_party/printf/",
+            "third_party/musl/include",
+            "third_party/musl/arch/generic",
+            "third_party/musl/arch/x86_64",
+            "third_party/musl/src/internal",
+            // directories for picolibc
+            "third_party/picolibc/libc/include",
+            "third_party/picolibc/libc/stdio",
+            "include",
+        ];
+
+        for dir in include_dirs {
+            let include_src_dir = libc_dir.join(dir);
+            let files = glob::glob(&format!("{}/**/*.h", include_src_dir.display()))
+                .context("Failed to read include source directory")?;
+            for file in files {
+                let src = file.context("Failed to read include source file")?;
+                let dst = src.strip_prefix(&include_src_dir).unwrap();
+                let dst = include_dst_dir.join(dst);
+
+                std::fs::create_dir_all(dst.parent().unwrap())
+                    .context("Failed to create include subdirectory")?;
+                std::fs::copy(&src, &dst).context("Failed to copy include file")?;
+            }


@ludfjig I think you added this---is there more nuance here?

I'm pretty sure even like this this the C simpleguest at least was working, but I'm not sure if it actually uses any libc functions.

Hmm I can't remember, I think I did this when our musl was x86 only to skip it for aarch64, but might not be relevant since we use picolibc which I think has aarch64 support

+        let mut skip_next = false;
+        for arg in args.iter() {
+            if skip_next {
+                skip_next = false;
+                continue;
+            }
+            let arg_str = arg.to_string_lossy();
+            if arg_str == "--target" || arg_str == "--target-dir" {
+                skip_next = true; // skip the next arg (the value)
+                continue;


 pub fn find_cargo() -> Result<CargoBinary> {
    let cargo = match env::var_os("CARGO") {
-        Some(cargo) => Path::new(&cargo).canonicalize()?,
-        None => which::which("cargo")?.canonicalize()?,
+        Some(cargo) => PathBuf::from(cargo),
+        None => which::which("cargo")?,
    };


ludfjig force-pushed the aarch64 branch 3 times, most recently from 04c7534 to ddedf1c Compare March 10, 2026 18:39

ludfjig and others added 6 commits May 26, 2026 19:12

fixup! fix: strip --target and --target-dir from forwarded args

28ac7b5

Fix a Rust warning, hopefully fixing CI. Signed-off-by: Lucy Menon <168595099+syntactically@users.noreply.github.com>

syntactically force-pushed the aarch64 branch from ddedf1c to 28ac7b5 Compare May 26, 2026 18:29

ludfjig requested a review from Copilot May 27, 2026 17:41

Copilot started reviewing on behalf of ludfjig May 27, 2026 17:41 View session

Copilot AI reviewed May 27, 2026

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Add aarch64 support#32

Add aarch64 support#32
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ludfjig commented Mar 10, 2026 •

edited

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ludfjig commented Mar 10, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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ludfjig commented Mar 10, 2026 •

edited

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