linux-kernel - Re: [PATCH 1/5] x86/fpu: Fix math emulation in eager fpu mode

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Message-ID: <20160123175114.GE16329@pd.tnic>
Date:	Sat, 23 Jan 2016 18:51:14 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Andy Lutomirski <luto@...nel.org>, X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>,
	yu-cheng yu <yu-cheng.yu@...el.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Rik van Riel <riel@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 1/5] x86/fpu: Fix math emulation in eager fpu mode

On Sat, Jan 23, 2016 at 09:40:06AM -0800, Andy Lutomirski wrote:
> I'm confused.  I want to make use_eager_fpu() return true always, so
> how would this help?  The idea is for FPU emulation to work despite
> being in eager mode.

I mean this:

static __always_inline __pure bool use_eager_fpu(void)
{
	if (!static_cpu_has(X86_FEATURE_FPU))
		return false;

        return static_cpu_has(X86_FEATURE_EAGER_FPU);
}

Although now I realize that returning false is ambiguous here. F'get it.

-- 
Regards/Gruss,
    Boris.

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