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

[Pekka Enberg <penberg@kernel.org>]

  Hi Brian,

On 8/30/10 2:38 AM, Brian Gerst wrote:
> On Sun, Aug 29, 2010 at 3:00 PM, Pekka Enberg<penberg@kernel.org>  wrote:
>> On Sat, Aug 28, 2010 at 7:04 PM, Brian Gerst<brgerst@gmail.com>  wrote:
>>> Remove ifdefs for code that the compiler can optimize away on 64-bit.
>>>
>>> Signed-off-by: Brian Gerst<brgerst@gmail.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.
> FXSR is a required feature on 64-bit, therefore cpu_has_fxsr is always true.
Yes, I realize that but it will still read boot_cpu_data at runtime, no?

             Pekka