I have this working with LLVM/Clang, and a PR is filed for GCC because the current hacks we have to do to *try* to ensure that .code16gcc is the first thing in the asm output are horrid.
Signed-off-by: David Woodhouse <[email protected]> --- arch/x86/Makefile | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/arch/x86/Makefile b/arch/x86/Makefile index ef19271..60fc67d 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -13,14 +13,21 @@ endif # How to compile the 16-bit code. Note we always compile for -march=i386; # that way we can complain to the user if the CPU is insufficient. -REALMODE_CFLAGS := -m32 -g -Os -D__KERNEL__ -DDISABLE_BRANCH_PROFILING \ +# +# We really want GCC to have a -m16 option like clang, so that we don't +# have to play these evil and unreliable tricks to ensure that our +# asm(".code16gcc") is first in the asm output. http://gcc.gnu.org/PR59672 +CODE16GCC_CFLAGS := -m32 -include $(srctree)/arch/x86/boot/code16gcc.h \ + $(call cc-option, -fno-toplevel-reorder,\ + $(call cc-option, -fno-unit-at-a-time)) +M16_CFLAGS := -m16 + +REALMODE_CFLAGS := -g -Os -D__KERNEL__ -DDISABLE_BRANCH_PROFILING \ + $(call cc-option, $(M16_CFLAGS), $(CODE16GCC_CFLAGS)) \ -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \ - -include $(srctree)/arch/x86/boot/code16gcc.h \ -fno-strict-aliasing -fomit-frame-pointer -fno-pic \ -mno-mmx -mno-sse \ $(call cc-option, -ffreestanding) \ - $(call cc-option, -fno-toplevel-reorder,\ - $(call cc-option, -fno-unit-at-a-time)) \ $(call cc-option, -fno-stack-protector) \ $(call cc-option, -mpreferred-stack-boundary=2) export REALMODE_CFLAGS -- 1.8.4.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
