On Thu, Jul 18, 2019 at 02:34:44PM -0700, Nick Desaulniers wrote: > On Wed, Jul 17, 2019 at 5:02 PM Vaibhav Rustagi > <vaibhavrustagi@xxxxxxxxxx> wrote: > > > > Compiling the purgatory code with clang results in using of mmx > > registers. > > > > $ objdump -d arch/x86/purgatory/purgatory.ro | grep xmm > > > > 112: 0f 28 00 movaps (%rax),%xmm0 > > 115: 0f 11 07 movups %xmm0,(%rdi) > > 122: 0f 28 00 movaps (%rax),%xmm0 > > 125: 0f 11 47 10 movups %xmm0,0x10(%rdi) > > > > Add -mno-sse, -mno-mmx, -mno-sse2 to avoid generating SSE instructions. > > > > Signed-off-by: Vaibhav Rustagi <vaibhavrustagi@xxxxxxxxxx> > > --- > > arch/x86/purgatory/Makefile | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile > > index 3cf302b26332..3589ec4a28c7 100644 > > --- a/arch/x86/purgatory/Makefile > > +++ b/arch/x86/purgatory/Makefile > > @@ -20,6 +20,7 @@ KCOV_INSTRUMENT := n > > # sure how to relocate those. Like kexec-tools, use custom flags. > > > > KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss -fno-builtin -ffreestanding -c -Os -mcmodel=large > > +KBUILD_CFLAGS += -mno-mmx -mno-sse -mno-sse2 > > Yep, this is a commonly recurring bug in the kernel, observed again > and again for Clang builds. The top level Makefile carefully sets > KBUILD_CFLAGS, then lower subdirs in the kernel wipe them away with > `:=` assignment. Invariably important flags don't always get re-added. > In this case, these flags are used in arch/x86/Makefile, but not here > and should be IMO. Thanks for the patch. Should we then not fix/remove these := assignments?
