Re: [PATCH] lockup_detector: Make DETECT_HUNT_TASK default depend onLOCKUP_DETECTOR

From: Ingo Molnar
Date: Sat Aug 07 2010 - 03:02:35 EST

(Linus Cc:-ed)

* Frederic Weisbecker <fweisbec@xxxxxxxxx> wrote:

> On Wed, Aug 04, 2010 at 09:53:03AM +0800, Li Zefan wrote:
> > CONFIG_DETECT_SOFTLOCKUP has been removed, so switch the
> > default value to LOCKUP_DETECTOR.
> >
> > Also fix the help text of BOOT_PRINTK_DELAY.
> >
> > Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
> > ---
> Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> Thanks.

The thing is, CONFIG_DETECT_SOFTLOCKUP was default-y before, so many people
had it enabled [and had it forced-enabled if DEBUG_KERNEL was off], even if
they didnt really want or need it.

So i turned off the new generic watchdog code's default intentionally - as it
clearly does not cure cancer ;-)

I think distros will enable it, and most testers will as well. Those who dont
enable it and run into a lockup have an easy option to enable.

Maybe a better change would be to make it more generally available - right now

bool "Detect Hard and Soft Lockups"
depends on DEBUG_KERNEL && !S390

which means that it cannot be enabled when DEBUG_KERNEL is off.

So i think we should:

- Remove the s390 hack and add an ARCH_HAS_LOCKUP_DETECTOR flag
- Remove the DEBUG_KERNEL dependency



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