From dd4611dea435d77dcc8f695c35b15c4a2cc1e55f Mon Sep 17 00:00:00 2001 From: Bin Meng Date: Sat, 13 Oct 2018 20:52:02 -0700 Subject: [PATCH] x86: Ensure no instruction sets of MMX/SSE are generated in 64-bit build With the '-march=core2' fix, it seems that we have some luck that the 64-bit U-Boot boots again. However if we examine the disassembly codes there are still SSE instructions elsewhere which means passing cpu type to GCC is not enough to prevent it from generating these instructions. A simple test case is doing a 'bootefi selftest' from the U-Boot shell and it leads to a reset too. The 'bootefi selftest' reset is even seen with the image created by the relative older GCC 5.4.0, the one shipped by Ubuntu 16.04. The reset actually originates from undefined instruction exception caused by these SSE instructions. To keep U-Boot as a bootloader as simple as possible, we don't want to handle such advanced SIMD stuff. To make sure no MMX/SSE instruction sets are generated, tell GCC not to do this. Note AVX is out of the question as CORE2 is old enough to support AVX yet. Signed-off-by: Bin Meng Reviewed-by: Heinrich Schuchardt Reviewed-by: Simon Glass --- arch/x86/config.mk | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/config.mk b/arch/x86/config.mk index 576501e..8151e47 100644 --- a/arch/x86/config.mk +++ b/arch/x86/config.mk @@ -24,6 +24,7 @@ ifeq ($(IS_32BIT),y) PLATFORM_CPPFLAGS += -march=i386 -m32 else PLATFORM_CPPFLAGS += $(if $(CONFIG_SPL_BUILD),,-fpic) -fno-common -march=core2 -m64 +PLATFORM_CPPFLAGS += -mno-mmx -mno-sse endif PLATFORM_RELFLAGS += -fdata-sections -ffunction-sections -fvisibility=hidden