feat: add minimal C++ ABI stubs for freestanding kernel

1 files changed, 37 insertions, 0 deletions

diff --git a/na/lib/cxx_abi.cc b/na/lib/cxx_abi.cc
new file mode 100644
index 0000000..1ad9d4d
--- /dev/null
+++ b/na/lib/cxx_abi.cc
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (C) 2026 Richard Qin */
+
+/*
+ * cxx_abi.cc — Minimal C++ ABI stubs for freestanding kernel
+ *
+ * Provides symbols that the compiler/linker expects from the C++
+ * runtime library.  All error paths are fatal (kernel_panic).
+ *
+ * Reference: docs/specs/cpp_runtime.md
+ */
+
+#include <lume/panic.h>
+
+/* Pure virtual function call trap.
+ * Generated by the compiler in vtable entries for pure virtual methods.
+ * Reaching this means a derived class failed to implement a pure virtual. */
+extern "C" void __cxa_pure_virtual()
+{
+    kernel_panic("pure virtual function call");
+}
+
+/* Global destructor registration.
+ * The kernel does not support global object destruction — all global
+ * objects use Placement New with explicit lifetime management.
+ * If the compiler emits a call to this, it indicates a code violation. */
+extern "C" int __cxa_atexit(void (*)(void*), void*, void*)
+{
+    kernel_panic("__cxa_atexit called in kernel");
+    return 0; // unreachable
+}
+
+/* DSO handle — required by __cxa_atexit ABI.
+ * The kernel is statically linked; this symbol just needs to exist. */
+extern "C" {
+void* __dso_handle __attribute__((visibility("hidden"))) = nullptr;
+}