linux-kernel - Re: [PATCH 3/3] x86-64: Simplify loading initial

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Date:	Sat, 17 Jul 2010 19:14:38 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Brian Gerst <brgerst@...il.com>
Cc:	hpa@...or.com, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] x86-64: Simplify loading initial_gs

On Sat, Jul 17, 2010 at 4:03 PM, Brian Gerst <brgerst@...il.com> wrote:
> Load initial_gs as two 32-bit values instead of splitting a 64-bit value.
>
> Signed-off-by: Brian Gerst <brgerst@...il.com>
> ---
>  arch/x86/kernel/head_64.S |    5 ++---
>  1 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
> index 3d1e6f1..239046b 100644
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -234,9 +234,8 @@ ENTRY(secondary_startup_64)
>         * init data section till per cpu areas are set up.
>         */
>        movl    $MSR_GS_BASE,%ecx
> -       movq    initial_gs(%rip),%rax
> -       movq    %rax,%rdx
> -       shrq    $32,%rdx
> +       movl    initial_gs(%rip),%eax
> +       movl    initial_gs+4(%rip),%edx
>        wrmsr
>
>        /* esi is pointer to real mode structure with interesting info.

Reviewed-by: Pekka Enberg <penberg@...helsinki.fi>
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