Hi Heinrich, On Fri, Oct 12, 2018 at 2:04 AM Heinrich Schuchardt <xypron.g...@gmx.de> wrote: > > On 10/11/2018 03:53 AM, Bin Meng wrote: > > 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. > > I can confirm that an unexpected reset patch occurs without the patch. >
I think you mean "bootefi selftest" reset, right? > > > > 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. > > > > 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 <bmeng...@gmail.com> > > --- > > > > 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 > > According to https://wiki.osdev.org/SSE SSE has to be initialized. > Otherwise SSE instructions lead to an undefined instruction exception. > Is it this initialization that we lack? If this is your motivation > please, state it in the commit message. > Yes, it's intentional. U-Boot as a bootloader does not want to handle these advanced SIMD stuff. > I think this patch could be squashed with the prior one. They are different thing, although they solved similar reset. The first patch is adding the -march=core2 which is the counterpart of -march=i386 for 32-bit U-Boot. This patch is to disable MMX/SSE completely which I think deserve a separate patch. Regards, Bin _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
