Messages in this thread | | | Subject | Re: [PATCH] x86/fpu: Revert earlier patch of Disable AVX when eagerfpu is off | From | "H. Peter Anvin" <> | Date | Wed, 9 Mar 2016 10:51:45 -0800 |
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On 03/09/2016 04:46 AM, Ingo Molnar wrote: > > * Yu-cheng Yu <yu-cheng.yu@intel.com> wrote: > >> AVX was mistakenly believed to be dependent on eagerfpu switch. >> This turns out to be false. The earlier patch should be reverted. >> >> Original patch: >> http://git.kernel.org/tip/394db20ca240741a08d472173db13d6f6a6e5a28 > > So the original patch had a whole host of explanations of why that change is > correct. This revert should explain where that argumentation was wrong. > > Also note that eagerfpu=off is on the way out, on v4.6 we'll switch all CPUs to > eagerfpu: > > 58122bf1d856 x86/fpu: Default eagerfpu=on on all CPUs > > and in the not so distant future, if everything goes fine with the eager mode, I'd > like to drop the lazy FPU context switching code altogether - which will simplify > a lot of code. At that point the 'eagerfpu' boot option will go away as well. >
Last I heard the only use case which was seeing trouble with eagerfpu was KVM during service of I/O events. Might be worth checking into...
-hpa
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