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Date: Fri, 29 May 2015 18:10:36 +0200
From: Borislav Petkov <bp@alien8.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave@sr71.net>, Ingo Molnar <mingo@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        X86 ML <x86@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Oleg Nesterov <oleg@redhat.com>, Rik van Riel <riel@redhat.com>,
        Suresh Siddha <sbsiddha@gmail.com>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Fenghua Yu <fenghua.yu@intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH 02/19] x86, fpu: Wrap get_xsave_addr() to make it safer
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On Thu, May 28, 2015 at 06:05:33PM -0700, Andy Lutomirski wrote:
> I would propose that we take the opposite approach and just ban
> eagerfpu=off when MPX is enabled.  We could then take the next step
> and default eagerfpu=on for everyone and, if nothing breaks, then just
> delete lazy mode entirely.
> 
> I suspect we'd have to go back to Pentium 3 or earlier to find a CPU
> on which lazy mode is actually a good idea.

Last time I checked (and ran some benchmarks) it was only a minute
slowdown so I say we kill lazy mode if it means significant code
complexity drop.

Can I also emulate Greg here and suggest that Pentium 3 people should
buy newer hw? They should think about the environment, if nothing else.

:-P

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--