From d18992a3ea1df301d6cd15271400af33640f4b3f Mon Sep 17 00:00:00 2001
From: netbsduser <5460559+netbsduser@users.noreply.github.com>
Date: Mon, 14 Oct 2024 12:21:40 +0100
Subject: [PATCH] options/internal: ensure FutexLockImpl alignment to 4 bytes

On m68k the default alignment of 2 bytes for a uint32_t will
result in futex calls failing, as a futex must be 4-byte aligned.
---
 options/internal/include/mlibc/lock.hpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/options/internal/include/mlibc/lock.hpp b/options/internal/include/mlibc/lock.hpp
index 8bff98747..85ceb4e23 100644
--- a/options/internal/include/mlibc/lock.hpp
+++ b/options/internal/include/mlibc/lock.hpp
@@ -8,8 +8,12 @@
 #include <mlibc/tid.hpp>
 #include <bits/ensure.h>
 
+// alignas(4) is specified for the benefit of m68k, where default alignment is
+// 2 bytes for a uint32_t, while the futex syscall requires 4-byte alignment.
+// It is a no-op on any other architecture.
+
 template<bool Recursive>
-struct FutexLockImpl {
+struct alignas(4) FutexLockImpl {
 	FutexLockImpl() : _state{0}, _recursion{0} { }
 
 	FutexLockImpl(const FutexLockImpl &) = delete;