Re: [rfc] fix Kconfig, hotplug_cpu is needed for swsusp

[Nigel Cunningham]

Hi.

On Thursday 30 March 2006 09:09, Ashok Raj wrote:
> On Wed, Mar 29, 2006 at 02:47:46PM -0800, Andrew Morton wrote:
> > Pavel Machek <pavel@xxxxxx> wrote:
> > > HOTPLUG_CPU is needed on normal PCs, too -- it is neccessary for
> > > software suspend.
> >
> > OK, this will get ugly.  APICs are involved.
>
> I guess you need only on systems that support >1 cpu right? I doubt you
> will need it on a system that cannot run with the config-generic-arch on.
> although we use bigsmp when hotplug is turned on, all we really end up is
> using flat physical mode instead of using logical mode.
>
> I still havent understood why this wont work. Choosing
> CONFIG_X86_GENERICARCH shouldnt break anything AFAICT.
>
> Pavel, you could use CONFIG_HOTPLUG_CPU, just need to enable
> X86_GENERICARCH now. Is there a reason you think that wont work? I wish we
> would revert it for a strong reason that we know will not make hotplug work
> on certain systems because of this choise not that we currently have X86_PC
> now, and are unwiling to change the config.
>
> (PS: the word bigsmp although sounds like some large NR_CPUS, its just
> using a mode that permits the system to work from 1 .. >8 cpus. So there is
> really nothing determental to selecting this.)

So if you have a single core x86, you want X86_PC, and if you have HT or SMP, 
you want GENERICARCH? If so, could this be done via selects or depends or at 
least defaults in Kconfig?

Regards,

Nigel

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