Re: [PATCH] sched/x86: Save [ER]FLAGS on context switch

[Peter Zijlstra]

On Fri, Feb 15, 2019 at 09:18:00AM -0800, Linus Torvalds wrote:
> On Thu, Feb 14, 2019 at 11:34 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> >
> > Something like the below, right?
> >
> > +       frame->flags = 0;
> > +       frame->flags = 0;
> 
> Those are not valid flag values.
> 
> Can you popf them? Yes.
> 
> Do they make sense? No.
> 
> It has the IF flag clear, for example. Is that intentional? If it is,

Uhmm. yeah, that's bonkers. We should have interrupts disabled here.
I'll go read up on the eflags and figure out what they _should_ be right
about there.