Re: [PATCH] x86/fpu: Revert earlier patch of Disable AVX when eagerfpu is off

From: Ingo Molnar
Date: Wed Mar 09 2016 - 07:46:42 EST

* Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx> 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:

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

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.