On Thursday, July 28, 2016 01:20:53 AM Rafael J. Wysocki wrote: > On Wednesday, July 27, 2016 05:17:38 PM Josh Poimboeuf wrote: > > On Thu, Jul 28, 2016 at 12:12:15AM +0200, Rafael J. Wysocki wrote: > > > On Wednesday, July 27, 2016 12:59:18 PM Josh Poimboeuf wrote: > > > > Hm... I have a theory, but I'm not sure about it. I noticed that > > > > x86_acpi_enter_sleep_state(), > > > > > > I think you mean x86_acpi_suspend_lowlevel(). > > > > Oops! > > > > > > which is involved in suspend, overwrites > > > > several global variables (e.g, initial_code) which are used by the CPU > > > > boot code in head_64.S. But surprisingly, it doesn't restore those > > > > variables to their original values after it resumes. > > > > > > Is the head_64.S code also used to bring up offline CPUs? > > > > Yes. > > OK > > So it is really interesting why and how that stuff works for everybody. > > Basically, CPU online should fail after a suspend-resume cycle, but it > doesn't most of the time AFAICS.
do_boot_cpu() restores those values, so I think we're safe from that angle. That should apply to the CPU online during resume from hibernation too. Thanks, Rafael
