Re: [PATCH v4] x86/power: Fix 'nosmt' vs. hibernation triple fault during resume

[Jiri Kosina]

On Fri, 31 May 2019, Josh Poimboeuf wrote:

> > I disagree with that from the backwards compatibility point of view.
> > 
> > I personally am quite frequently using differnet combinations of 
> > resumer/resumee kernels, and I've never been biten by it so far. I'd guess 
> > I am not the only one.
> > Fixmap sort of breaks that invariant.
> 
> Right now there is no backwards compatibility because nosmt resume is
> already broken.

Yeah, well, but that's "only" for nosmt kernels at least.

> For "future" backwards compatibility we could just define a hard-coded 
> reserved fixmap page address, adjacent to the vsyscall reserved address.
> 
> Something like this (not yet tested)?  Maybe we could also remove the
> resume_play_dead() hack?

Does it also solve cpuidle case? I have no overview what all the cpuidle 
drivers might be potentially doing in their ->enter_dead() callbacks. 
Rafael?

Thanks,

-- 
Jiri Kosina
SUSE Labs