Hi Stewart, On Wed, Oct 12, 2016 at 04:35:35PM +1100, Stewart Smith wrote: > > What if we just treat the 0xF state from firmware as special and set it > to DEFAULT_PSSCR_MASK in that case? That deals with old skiboot, new > kernel, and sets a pretty small special case that's easy to track into > the future as something we should watch out for.
Yes, that will work. I will use this approach in the next version. > > Additionally, if we make skiboot set sane values in ~DEFAULT_PSSCR_MASK > for valid fields in PSSCR on boot/(also kexec?), then > we should end up in a situation where everything works with everything > (even if you don't get the best power saving). Specifically, new > skiboot, old kernel... but it looks like there's nothing currently > missing there No we're not missing much there. From the code of the old kernel, I see that if we pass the psscr_val instead of just the RL to power9_idle_stop(), we end up saving all the SPRs in power_enter_stop() even if the psscr_val didn't correspond to a deep idle state. But that should be ok. > > Should this patch also have Fixes: 3005c597ba4 and CC to stable? Yes, thanks for pointing it out. I shall mark the next version to stable. > > -- > Stewart Smith > OPAL Architect, IBM. -- Thanks and Regards gautham.