Setup cross compilation for aarhc64-unknown-freebsd

Cargo.toml

@@ -335,6 +335,9 @@ default = [
   # By default include compatibility with the "old" CLI from Wasmtime 13 and
   # prior.
   "old-cli",
+
+  # remove later, just on for convenience
+  "cheri",
 ]
 
 # ========================================

Cross.toml

@@ -0,0 +1,6 @@
+[target.aarch64-unknown-freebsd]
+# We need to build std, as aarch64-unknown-freebsd is not a tier 1 rust target
+build-std = true
+image.name = "ghcr.io/cross-rs/aarch64-unknown-freebsd:local"
+image.toolchain = ["linux/arm64/v8=aarch64-unknown-linux-gnu"]
+

docs/cheri-cross-compilation.md

@@ -0,0 +1,70 @@
+# Cross-Compilation
+
+Since `aarch64-unknown-freebsd` is not a Rust tier-1 target, we use [cross](https://github.com/cross-rs/cross) to cross-compile for it.
+
+We need the latest `cross` binary, as well as a custom docker image.
+
+```shell
+git clone https://github.com/cross-rs/cross.git
+```
+
+Then, apply the following patch:
+
+```patch
+From 49ed9ce2082116ac41f80afef1e7c9390d358cd3 Mon Sep 17 00:00:00 2001
+From: Martin Fink <[email protected]>
+Date: Wed, 21 Feb 2024 17:46:53 +0100
+Subject: [PATCH] add link
+
+---
+ docker/Dockerfile.aarch64-unknown-freebsd | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/docker/Dockerfile.aarch64-unknown-freebsd b/docker/Dockerfile.aarch64-unknown-freebsd
+index 8631717..d03726a 100644
+--- a/docker/Dockerfile.aarch64-unknown-freebsd
++++ b/docker/Dockerfile.aarch64-unknown-freebsd
+@@ -31,6 +31,8 @@ COPY freebsd-fetch-best-mirror.sh /
+ COPY freebsd-setup-packagesite.sh /
+ COPY freebsd-install-package.sh /
+
++RUN ln -s $(which gcc) /usr/local/bin/aarch64-unknown-linux-gnu-gcc
++
+ ENV CARGO_TARGET_AARCH64_UNKNOWN_FREEBSD_LINKER="$CROSS_TOOLCHAIN_PREFIX"gcc.sh \
+     AR_aarch64_unknown_freebsd="$CROSS_TOOLCHAIN_PREFIX"ar \
+     CC_aarch64_unknown_freebsd="$CROSS_TOOLCHAIN_PREFIX"gcc \
+-- 
+2.43.0
+```
+
+and run the following (assuming you are running on an AArch64 machine).
+
+```shell
+cargo build-docker-image \                                                                                                                                                                                                                                                                                                                                             
+    --platform=aarch64-unknown-linux-gnu \
+    aarch64-unknown-freebsd \
+    --tag local
+```
+
+If you're on X86, run:
+
+```shell
+cargo build-docker-image \                                                                                                                                                                                                                                                                                                                                             
+    aarch64-unknown-freebsd \
+    --tag local
+```
+
+Then, install the latest version of `cross`:
+
+```shell
+cargo install --git https://github.com/cross-rs/cross.git cross 
+```
+
+Now, you can cross-compile for `aarch64-unknown-freebsd`:
+
+```shell
+rustup override set nightly
+cross build --target aarch64-unknown-freebsd --release
+```
+
+The built binary can be found in `target/aarch64-unknown-freebsd/release/`.