From a9cfccee6604854aebc70215610b9788667f4fec Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Wed, 4 Jun 2014 13:16:48 -0700 Subject: x86, build: Change code16gcc.h from a C header to an assembly header By changing code16gcc.h from a C header to an assembly header and use the -Wa,... option to gcc to force it to be added to the assembly input, we can avoid the problems with gcc reordering code bits on us. If we have -m16, we still use it, of course. Suggested-by: Kevin O'Connor Signed-off-by: H. Peter Anvin Link: http://lkml.kernel.org/n/tip-xw8ibgdemucl9fz3i1bymu6w@git.kernel.org --- arch/x86/boot/code16gcc.h | 24 ++++++++++-------------- 1 file changed, 10 insertions(+), 14 deletions(-) (limited to 'arch/x86/boot/code16gcc.h') diff --git a/arch/x86/boot/code16gcc.h b/arch/x86/boot/code16gcc.h index d93e48010b6..5ff42653539 100644 --- a/arch/x86/boot/code16gcc.h +++ b/arch/x86/boot/code16gcc.h @@ -1,15 +1,11 @@ -/* - * code16gcc.h - * - * This file is -include'd when compiling 16-bit C code. - * Note: this asm() needs to be emitted before gcc emits any code. - * Depending on gcc version, this requires -fno-unit-at-a-time or - * -fno-toplevel-reorder. - * - * Hopefully gcc will eventually have a real -m16 option so we can - * drop this hack long term. - */ +# +# code16gcc.h +# +# This file is added to the assembler via -Wa when compiling 16-bit C code. +# This is done this way instead via asm() to make sure gcc does not reorder +# things around us. +# +# gcc 4.9+ has a real -m16 option so we can drop this hack long term. +# -#ifndef __ASSEMBLY__ -asm(".code16gcc"); -#endif + .code16gcc -- cgit v1.2.3-70-g09d2