linux-kernel - Re: [PATCH 2/4] x86/fpu: introduce restore_init

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Date:	Mon, 16 Mar 2015 15:05:06 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Borislav Petkov <bp@...e.de>, Oleg Nesterov <oleg@...hat.com>
CC:	Dave Hansen <dave.hansen@...el.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Pekka Riikonen <priikone@....fi>,
	Suresh Siddha <sbsiddha@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	Quentin Casasnovas <quentin.casasnovas@...cle.com>
Subject: Re: [PATCH 2/4] x86/fpu: introduce restore_init_xstate()

On 03/13/2015 11:20 AM, Borislav Petkov wrote:
> On Fri, Mar 13, 2015 at 03:39:28PM +0100, Oleg Nesterov wrote:
>> This too needs cleanups. But later ;)
>>
>> Note that xstate_enable_boot_cpu is not called if !cpu_has_xsave, see the
>> check in xsave_init(). Howver, eagerfpu=on will force eager_fpu_init() which
>> calls eager_fpu_init_bp().
>
> Yahaa.
>
> This FPU cleanup fun will keep us busy until Christmas.
>
>> Btw, I was also going to kill eager_fpu_init_bp(). Probably I will
>> send the patch today.
>
> Yap, and I'm wondering if we should kill those func ptrs games there. We
> have BSP and AP CPU init paths so we can be much cleaner there.

I'll wait with the optimization that defers FPU state
loading to the kernel -> user space boundary, until this
current stuff has stabilized...

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