linux-kernel - Re: Linux patch disabling AVX when eagerfpu is turned off

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Message-ID: <56A13AC7.2040601@intel.com>
Date:	Thu, 21 Jan 2016 12:08:39 -0800
From:	Dave Hansen <dave.hansen@...el.com>
To:	Leonid Shatz <leonid.shatz@...ellosystems.com>,
	'Ingo Molnar' <mingo@...nel.org>, linux-kernel@...r.kernel.org,
	'Yu-cheng Yu' <yu-cheng.yu@...el.com>,
	'Andy Lutomirski' <luto@...capital.net>,
	'Borislav Petkov' <bp@...en8.de>,
	'Fenghua Yu' <fenghua.yu@...el.com>,
	"'H. Peter Anvin'" <hpa@...or.com>,
	'Linus Torvalds' <torvalds@...ux-foundation.org>,
	'Oleg Nesterov' <oleg@...hat.com>,
	'Peter Zijlstra' <peterz@...radead.org>,
	'Quentin Casasnovas' <quentin.casasnovas@...cle.com>,
	"'Ravi V. Shankar'" <ravi.v.shankar@...el.com>,
	'Sai Praneeth Prakhya' <sai.praneeth.prakhya@...el.com>,
	'Thomas Gleixner' <tglx@...utronix.de>
Cc:	liran.alon@...ellosystems.com, mendel.aizner@...ellosystems.com,
	'Elazar Leibovich' <elazar.leibovich@...ellosystems.com>,
	'Eyal Moscovici' <eyal.moscovici@...ellosystems.com>,
	gil.hoffer@...ellosystems.com
Subject: Re: Linux patch disabling AVX when eagerfpu is turned off - possibly
 not required

On 01/21/2016 02:33 AM, Leonid Shatz wrote:
> In view of above findings we would like to suggest to double check if
> disabling AVX together with "eagerfpu off" is actually required and is a
> real necessity. It would be helpful to consult with Intel engineers
> regarding related design details.

Hi Leonid,

Thanks for the report!

Are you aware of any actual eagerfpu=off use in practice, or is this
mostly a theoretical concern?