From 985b12ffa6d526bbf3a884cfcc12907a0a4205bd Mon Sep 17 00:00:00 2001
From: Zou Guangxian <zouguangxian@gmail.com>
Date: Mon, 26 Jan 2026 04:14:53 +0000
Subject: [PATCH] feat(build): add support for custom RUSTFLAGS in
 build_binary_with_rustflags function

---
 build-syscall-cycles.sh               | 10 ++++++----
 crates/zeroos-build/src/cmds/build.rs |  6 ++++++
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/build-syscall-cycles.sh b/build-syscall-cycles.sh
index 47d67fa..fa3da82 100755
--- a/build-syscall-cycles.sh
+++ b/build-syscall-cycles.sh
@@ -14,11 +14,13 @@ cd "${ROOT}"
 echo "Building syscall-cycles example in std mode ..."
 if [[ "${PROFILE}" = "release" ]]; then
 	# Keep release profile tuning explicit (avoid per-crate [profile.release] warnings).
+	# Disable machine outliner to avoid OUTLINED_FUNCTION_* symbols interfering with cycle counts.
 	CARGO_PROFILE_RELEASE_DEBUG=2 \
-	CARGO_PROFILE_RELEASE_STRIP=none \
-	CARGO_PROFILE_RELEASE_LTO=true \
-	CARGO_PROFILE_RELEASE_CODEGEN_UNITS=1 \
-	cargo spike build -p syscall-cycles --target "${TARGET_TRIPLE}" --mode std -- --quiet --features=std --profile "${PROFILE}"
+		CARGO_PROFILE_RELEASE_STRIP=none \
+		CARGO_PROFILE_RELEASE_LTO=true \
+		CARGO_PROFILE_RELEASE_CODEGEN_UNITS=1 \
+		RUSTFLAGS="${RUSTFLAGS:-} -Cllvm-args=-enable-machine-outliner=never" \
+		cargo spike build -p syscall-cycles --target "${TARGET_TRIPLE}" --mode std -- --quiet --features=std --profile "${PROFILE}"
 else
 	cargo spike build -p syscall-cycles --target "${TARGET_TRIPLE}" --mode std -- --quiet --features=std --profile "${PROFILE}"
 fi
diff --git a/crates/zeroos-build/src/cmds/build.rs b/crates/zeroos-build/src/cmds/build.rs
index 01d5a44..9ed829f 100644
--- a/crates/zeroos-build/src/cmds/build.rs
+++ b/crates/zeroos-build/src/cmds/build.rs
@@ -193,6 +193,12 @@ pub fn build_binary_with_rustflags(
         .map(|s| s.split('\x1f').map(|s| s.to_string()).collect())
         .unwrap_or_default();
 
+    if let Ok(rustflags) = std::env::var("RUSTFLAGS") {
+        for flag in rustflags.split_whitespace() {
+            rustflags_parts.push(flag.to_string());
+        }
+    }
+
     // In unwind-table-based backtraces, we need DWARF CFI tables even with `panic=abort`.
     // This forces `.eh_frame` emission for Rust code when backtraces are enabled.
     if args.mode == StdMode::Std && backtrace_enabled {