linux-kernel - Re: [PATCH 10/11] x86: Remove unnecessary ifdefs from i387 code.

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Message-ID: <AANLkTik7Gv3xoZphR0VRkHdr3Z1tvO484S-zkYncC2K7@mail.gmail.com>
Date:	Sun, 29 Aug 2010 19:38:57 -0400
From:	Brian Gerst <brgerst@...il.com>
To:	Pekka Enberg <penberg@...nel.org>
Cc:	hpa@...or.com, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 10/11] x86: Remove unnecessary ifdefs from i387 code.

On Sun, Aug 29, 2010 at 3:00 PM, Pekka Enberg <penberg@...nel.org> wrote:
> On Sat, Aug 28, 2010 at 7:04 PM, Brian Gerst <brgerst@...il.com> wrote:
>> Remove ifdefs for code that the compiler can optimize away on 64-bit.
>>
>> Signed-off-by: Brian Gerst <brgerst@...il.com>
>
>> @@ -74,10 +74,8 @@ static void __cpuinit init_thread_xstate(void)
>>
>>        if (cpu_has_fxsr)
>>                xstate_size = sizeof(struct i387_fxsave_struct);
>> -#ifdef CONFIG_X86_32
>>        else
>>                xstate_size = sizeof(struct i387_fsave_struct);
>> -#endif
>>  }
>
> I guess this is OK but keep in mind that cpu_has_fsxr is _not_
> optimized by the compiler on 64-bit so the change probably increases
> kernel text by few bytes.
>
> Acked-by: Pekka Enberg <penberg@...nel.org>
>

FXSR is a required feature on 64-bit, therefore cpu_has_fxsr is always true.

--
Brian Gerst
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