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

[Pavel Machek <pavel@ucw.cz>]

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@sisk.pl> 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@sisk.pl>
> > > Acked-by: Pavel Machek <pavel@ucw.cz>
> > > ---
> > >  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
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