[PATCH] x86: use invd instead of wbinvd in real mode start code

[Masahiro Yamada]

I do not know why the boot code immediately after the system reset
should write-back the cache content. I think the cache invalidation
should be enough.

I tested this commit with qemu-x86_defconfig, and it worked for me.

Signed-off-by: Masahiro Yamada <masahiroy at kernel.org>
---

 arch/x86/cpu/start.S   | 2 +-
 arch/x86/cpu/start16.S | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S
index 01524635e9c8..26cf995db2d0 100644
--- a/arch/x86/cpu/start.S
+++ b/arch/x86/cpu/start.S
@@ -50,7 +50,7 @@ _x86boot_start:
 	movl	%cr0, %eax
 	orl	$(X86_CR0_NW | X86_CR0_CD), %eax
 	movl	%eax, %cr0
-	wbinvd
+	invd
 
 	/*
 	 * Zero the BIST (Built-In Self Test) value since we don't have it.
diff --git a/arch/x86/cpu/start16.S b/arch/x86/cpu/start16.S
index 54f4ff6662a8..292e75050814 100644
--- a/arch/x86/cpu/start16.S
+++ b/arch/x86/cpu/start16.S
@@ -28,7 +28,7 @@ start16:
 	movl	%cr0, %eax
 	orl	$(X86_CR0_NW | X86_CR0_CD), %eax
 	movl	%eax, %cr0
-	wbinvd
+	invd
 
 	/* load the temporary Global Descriptor Table */
 data32 cs	lidt	idt_ptr
-- 
2.17.1