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

[Rafael J. Wysocki]

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 .

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?

Rafael


-- 
You never change things by fighting the existing reality.
		R. Buckminster Fuller
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