Re: RFC: Petition Intel/AMD to add POPF_IF insn

[Linus Torvalds]

On Wed, Aug 17, 2016 at 2:26 PM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Of course, if somebody uses native_restore_fl() to actually *disable*
> interrupts (when they weren't already disabled), then this untested
> patch will just not work. But why would you do somethign so stupid?
> Famous last words...

Looking around, the vsmp code actually uses "native_restore_fl()" to
not just set the interrupt flag, but AC as well.

And the PV spinlock case has that "push;popf" sequence encoded in an alternate.

So that trivial patch may (or may not - still not tested) work for
some quick testing, but needs more effort for any *real* use.

                  Linus