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

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@kernel.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S
index 0152463..26cf995 100644 (file)
--- 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 54f4ff6..292e750 100644 (file)
--- 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