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

[Andrew Morton <akpm@osdl.org>]

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?