With newer kernel.org GCC (7.3.0 or 8.1.0), the u-boot.rom image built for qemu-x86_64 target does not boot. It keeps resetting soon after the 32-bit SPL jumps to 64-bit proper. Debugging shows that the reset happens inside env_callback_init().
000000000113dd85 <env_callback_init>: 113dd85: 41 54 push %r12 113dd87: 55 push %rbp 113dd88: 31 c0 xor %eax,%eax 113dd8a: 53 push %rbx 113dd8b: 0f 57 c0 xorps %xmm0,%xmm0
Executing "xorps %xmm0,%xmm0" causes CPU to immediately reset. However older GCC like 5.4.0 (the one shipped by Ubuntu 16.04) does not generate such instructions that utilizes SSE for this function - env_callback_init() and U-Boot boots without any issue. Explicitly specifying -march=core2 for newer GCC allows U-Boot proper to boot again. Examine assembly codes of env_callback_init and there is no SSE instruction in that function hence U-Boot continues to boot.
core2 seems to be the oldest arch in GCC that supports 64-bit. Like 32-bit U-Boot build we use -march=i386 which is the most conservative cpu type so that the image can run on any x86 processor, let's do the same for the 64-bit U-Boot build.
Signed-off-by: Bin Meng bmeng.cn@gmail.com Reviewed-by: Heinrich Schuchardt xypron.glpk@gmx.de Reviewed-by: Simon Glass sjg@chromium.org ---
arch/x86/config.mk | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/config.mk b/arch/x86/config.mk index cc94071..576501e 100644 --- a/arch/x86/config.mk +++ b/arch/x86/config.mk @@ -23,7 +23,7 @@ endif ifeq ($(IS_32BIT),y) PLATFORM_CPPFLAGS += -march=i386 -m32 else -PLATFORM_CPPFLAGS += $(if $(CONFIG_SPL_BUILD),,-fpic) -fno-common -m64 +PLATFORM_CPPFLAGS += $(if $(CONFIG_SPL_BUILD),,-fpic) -fno-common -march=core2 -m64 endif
PLATFORM_RELFLAGS += -fdata-sections -ffunction-sections -fvisibility=hidden