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

From: Pavel Machek
Date: Thu Mar 30 2006 - 03:28:19 EST


On St 29-03-06 15:09:51, 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.

If X86_GENERICARCH is not breaking anything, why does X86_PC exist? If
you say X86_GENERICARCH is okay for everyone, at least help texts need
to be fixed.

config X86_PC
bool "PC-compatible"
help
Choose this option if your computer is a standard PC or compatible.

config X86_BIGSMP
bool "Support for other sub-arch SMP systems with more than 8 CPUs"
depends on SMP
help
This option is needed for the systems that have more than 8 CPUs
and if the system is not of any sub-arch type above.

If you don't have such a system, you should say N here.

I certainly have PCtype machine here, and definitely not more than 8 CPUs.

> 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.)

At least config texts need to be fixed if you want people to use
X86_BIGSMP. And why keep X86_PC when X86_BIGSMP works as well?

Pavel
--
Picture of sleeping (Linux) penguin wanted...
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