Properly bootstrap new target

Author: lrettig

build.sh

@@ -8,9 +8,38 @@ source config.sh
 need_cmd clang
 need_cmd clang++
 
-# Rust requires a custom target file to exist for our custom target as part of the bootstrap build,
-# but it doesn't actually look at the contents.
-touch /tmp/riscv32em-athena-zkvm-elf.json
+# We need to bootstrap the new target for Rust
+cat > /tmp/riscv32em-athena-zkvm-elf.json << EOF
+{
+  "arch": "riscv32",
+  "cpu": "generic-rv32",
+  "crt-objects-fallback": "false",
+  "data-layout": "e-m:e-p:32:32-i64:64-n32-S32",
+  "eh-frame-header": false,
+  "emit-debug-gdb-scripts": false,
+  "features": "+e,+m",
+  "linker": "rust-lld",
+  "linker-flavor": "gnu-lld",
+  "llvm-abiname": "ilp32e",
+  "llvm-target": "riscv32",
+  "max-atomic-width": 32,
+  "os": "zkvm",
+  "panic-strategy": "abort",
+  "relocation-model": "static",
+  "singlethread": true,
+  "target-pointer-width": "32",
+  "vendor": "athena",
+  "options": {
+    "c-flags": "-march=rv32e -mabi=ilp32e",
+    "pre-link-args": {
+      "gcc": [
+        "-march=rv32e",
+        "-mabi=ilp32e"
+      ]
+    }
+  }
+}
+EOF
 export RUST_TARGET_PATH="/tmp"
 
 # Explicitly set CFLAGS without the problematic flags