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Subject: Re: Linux patch disabling AVX when eagerfpu is turned off - possibly
 not required
To: Leonid Shatz <leonid.shatz@ravellosystems.com>,
        "'Ingo Molnar'" <mingo@kernel.org>, linux-kernel@vger.kernel.org,
        "'Yu-cheng Yu'" <yu-cheng.yu@intel.com>,
        "'Andy Lutomirski'" <luto@amacapital.net>,
        "'Borislav Petkov'" <bp@alien8.de>,
        "'Fenghua Yu'" <fenghua.yu@intel.com>,
        "'H. Peter Anvin'" <hpa@zytor.com>,
        "'Linus Torvalds'" <torvalds@linux-foundation.org>,
        "'Oleg Nesterov'" <oleg@redhat.com>,
        "'Peter Zijlstra'" <peterz@infradead.org>,
        "'Quentin Casasnovas'" <quentin.casasnovas@oracle.com>,
        "'Ravi V. Shankar'" <ravi.v.shankar@intel.com>,
        "'Sai Praneeth Prakhya'" <sai.praneeth.prakhya@intel.com>,
        "'Thomas Gleixner'" <tglx@linutronix.de>
References: <02fd01d15437$233056c0$69910440$@ravellosystems.com>
Cc: liran.alon@ravellosystems.com, mendel.aizner@ravellosystems.com,
        "'Elazar Leibovich'" <elazar.leibovich@ravellosystems.com>,
        "'Eyal Moscovici'" <eyal.moscovici@ravellosystems.com>,
        gil.hoffer@ravellosystems.com
From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <56A13AC7.2040601@intel.com>
Date: Thu, 21 Jan 2016 12:08:39 -0800
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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?