Re: ftraced and suspend to ram

From: Steven Rostedt
Date: Fri Aug 22 2008 - 16:55:27 EST



On Fri, 22 Aug 2008, Rafael J. Wysocki wrote:
> > > tracing. Certainly all the assembly functions.
> >
> > I'm looking into that now too. Are the functions in arch/x86/power/cpu*.c
> > the suspend to ram code?
>
> They contain code executed during suspend to RAM, but such code is also:
> - in all files under arch/x86/kernel/acpi/
> - in main.c, console.c under kernel/power
> - in all files under drivers/acpi/sleep
> - in drivers/acpi/hardware/hwsleep.c
>
> Generally, ACPI is heavily involved and I'm not the right person to ask which
> of the ACPI functions should get the 'notrace' thing. Also, I'm not sure about
> the device drivers' ->suspend() and ->resume() callbacks, especially for
> sysdevs and ->suspend_late(), ->resume_early() for platform devices and PCI.
>
> Well, how exactly suspend to RAM is broken by ftrace?
>

I know that the smp_processor_id may be defined in the %fs register, but
if ftrace is called before the %fs is set up, it may crash because it
uses smp_processor_id.

-- Steve

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