Re: [PATCH 3/3] PM: Remove PM_TRACE from Kconfig

From: Pavel Machek
Date: Thu Aug 17 2006 - 05:11:59 EST


On Thu 2006-08-17 07:32:39, Rafael J. Wysocki wrote:
> On Wednesday 16 August 2006 23:52, Andrew Morton wrote:
> > On Wed, 16 Aug 2006 23:05:33 +0200
> > "Rafael J. Wysocki" <rjw@xxxxxxx> wrote:
> >
> > > Remove the CONFIG_PM_TRACE option, which is dangerous and should only be used
> > > by people who know exactly what they are doing, from kernel/power/Kconfig .
> > >
> > > Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
> > > Acked-by: Pavel Machek <pavel@xxxxxx>
> > > ---
> > > kernel/power/Kconfig | 18 ------------------
> > > 1 files changed, 18 deletions(-)
> > >
> > > Index: linux-2.6.18-rc4-mm1/kernel/power/Kconfig
> > > ===================================================================
> > > --- linux-2.6.18-rc4-mm1.orig/kernel/power/Kconfig
> > > +++ linux-2.6.18-rc4-mm1/kernel/power/Kconfig
> > > @@ -47,24 +47,6 @@ config PM_DISABLE_CONSOLE_SUSPEND
> > > suspend/resume routines, but may itself lead to problems, for example
> > > if netconsole is used.
> > >
> > > -config PM_TRACE
> > > - bool "Suspend/resume event tracing"
> > > - depends on PM && PM_DEBUG && X86_32 && EXPERIMENTAL
> > > - default n
> > > - ---help---
> > > - This enables some cheesy code to save the last PM event point in the
> > > - RTC across reboots, so that you can debug a machine that just hangs
> > > - during suspend (or more commonly, during resume).
> > > -
> > > - To use this debugging feature you should attempt to suspend the machine,
> > > - then reboot it, then run
> > > -
> > > - dmesg -s 1000000 | grep 'hash matches'
> > > -
> > > - CAUTION: this option will cause your machine's real-time clock to be
> > > - set to an invalid time after a resume.
> > > -
> > > -
> > > config SOFTWARE_SUSPEND
> > > bool "Software Suspend"
> > > depends on PM && SWAP && (X86 && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP)
> >
> > So... how are people supposed to turn it on again? By patching the
> > kernel? That's a bit painful if they're using (say) fedora-of-the-day.
> >
> > How about we add a kernel boot parameter to enable it at runtime?
>
> I'm considering a sysfs attribute in /sys/power .

Okay, that would work...

> If PM_TRACE is compiled in, an attribute, say "pm_trace", shows up in sysfs
> which is initially set to 0 and the user has to explicitly set it to 1 to
> enable the feature? Pavel, what do you think?

...I'd call it pm_trace_trash_my_time :-), and am wondering if we are
not overengineering this. I should have NAKed Linus' patch in the
first place, unfortunately I did not realize it was enabled by
default.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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