Re: [External] Re: [PATCH v9 0/8] Parallel CPU bringup for x86_64

[Thomas Gleixner]

On Wed, Feb 22 2023 at 08:19, David Woodhouse wrote:
> But the BSP/CPU0 is different. It hasn't actually been taken offline,
> and its idle thread context is still in cpu_startup_entry(CPUHP_ONLINE)
> which got called from rest_init().
>
> In testing I probably got away with it because we're only using the
> *top* of the stack, don't use anything of the red zone, and thus don't
> actually bother the true idle thread which is never going to return.

:)

> But I don't think it's correct; we really ought to have that temp_stack
> unless we're going to refactor the wakeup_64 code to *become* the idle
> thread just as startup_secondary() does, and *schedule* to the context
> that was saved in the suspend code.

And thereby messing up the scheduler state...

Thanks,

        tglx