From: H. Peter Anvin <hpa@zytor.com>
Date: Mon, 8 Sep 2008 19:01:48 +0000 (-0700)
Subject: x86: prevent binutils from being "smart" and generating NOPLs for us
X-Git-Tag: v2.6.28-rc1~699^2^3
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=28f7e66fc1da53997a545684b21b91fb3ca3f321;p=linux-2.6-omap-h63xx.git

x86: prevent binutils from being "smart" and generating NOPLs for us

binutils, contrary to documented behaviour, will generate long NOPs (a
P6-or-higher instruction which is broken on at least some VIA chips,
Virtual PC/Virtual Server, and some versions of Qemu) depending on the
-mtune= option, which is not supposed to change architectural
behaviour.

Pass an explicit override to the assembler, in case ends up passing
the -mtune= parameter to gas (gcc 4.3.0 does not appear to.)

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---

diff --git a/arch/x86/Makefile_32.cpu b/arch/x86/Makefile_32.cpu
index e372b584e91..b72b4f75311 100644
--- a/arch/x86/Makefile_32.cpu
+++ b/arch/x86/Makefile_32.cpu
@@ -45,3 +45,8 @@ cflags-$(CONFIG_MGEODEGX1)	+= -march=pentium-mmx
 # cpu entries
 cflags-$(CONFIG_X86_GENERIC) 	+= $(call tune,generic,$(call tune,i686))
 
+# Bug fix for binutils: this option is required in order to keep
+# binutils from generating NOPL instructions against our will.
+ifneq ($(CONFIG_X86_P6_NOP),y)
+cflags-y			+= $(call cc-option,-Wa$(comma)-mtune=generic32,)
+endif