On ARM, enabling the MMU is a prerequisite to enabling caching, which allows unaligned memory accesses by consolidating them into aligned accesses. When the MMU is disabled, however, all accesses must strictly adhere to the alignment rules.
Some compilers (e.g. Clang) contain optimizations that may break these rules on the assumption that misaligned accesses merely incur a performance penalty. We do not necessarily want to prevent the compiler from applying these optimizations where it believes there may be net gains, but we do need to tell it to respect the alignment requirements when the MMU is disabled. Therefore, add the `-mstrict-align` compiler flag when SYS_ARM_MMU is not set. Signed-off-by: Sam Edwards <cfswo...@gmail.com> --- arch/arm/config.mk | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm/config.mk b/arch/arm/config.mk index e0045e22271..98237b251f1 100644 --- a/arch/arm/config.mk +++ b/arch/arm/config.mk @@ -33,6 +33,10 @@ PLATFORM_RELFLAGS += $(LLVM_RELFLAGS) PLATFORM_CPPFLAGS += -D__ARM__ +ifneq ($(CONFIG_SYS_ARM_MMU),y) +PLATFORM_RELFLAGS += -mstrict-align +endif + ifdef CONFIG_ARM64 PLATFORM_ELFFLAGS += -B aarch64 -O elf64-littleaarch64 else -- 2.45.2
