Re: [RFC][PATCH] new timeofday arch specific hooks (v. A3)

[john stultz]

On Wed, 2005-03-16 at 00:44 +0100, Pavel Machek wrote:
> On Út 15-03-05 15:42:09, john stultz wrote:
> > On Tue, 2005-03-15 at 23:59 +0100, Pavel Machek wrote:
> > > > diff -Nru a/arch/i386/kernel/apm.c b/arch/i386/kernel/apm.c
> > > > --- a/arch/i386/kernel/apm.c	2005-03-11 17:02:30 -08:00
> > > > +++ b/arch/i386/kernel/apm.c	2005-03-11 17:02:30 -08:00
> > > > @@ -224,6 +224,7 @@
> > > >  #include <linux/smp_lock.h>
> > > >  #include <linux/dmi.h>
> > > >  #include <linux/suspend.h>
> > > > +#include <linux/timeofday.h>
> > > >  
> > > >  #include <asm/system.h>
> > > >  #include <asm/uaccess.h>
> > > > @@ -1204,6 +1205,7 @@
> > > >  	device_suspend(PMSG_SUSPEND);
> > > >  	device_power_down(PMSG_SUSPEND);
> > > >  
> > > > +	timeofday_suspend_hook();
> > > >  	/* serialize with the timer interrupt */
> > > >  	write_seqlock_irq(&xtime_lock);
> > > >  
> > > 
> > > Could you just register timeofday subsystem as a system device? Then
> > > device_power_down will call you automagically..... And you'll not have
> > > to modify apm, acpi, swsusp, ppc suspend, arm suspend, ...
> > 
> > That may very well be the right way to go. At the moment I'm just very
> > hesitant of making any user-visible changes.
> > 
> > What is the impact if a new system device name is created and then I
> > later change it? How stable is that interface supposed to be?
> 
> Changing its name is okay... your device probably will not have any
> user-accessible controls, right?

Well, at some point I want to have some way for the user to be able to
select which timesource they want to be used. Similar to the current
"clock=" boot option override, there would be some sort of sysfs
timesource entry that users could "echo tsc" or whatever into in order
to force the system to use the tsc timesource at runtime.

This however would be separate from the timeofday suspend/resume hooks,
so its probably not an issue. Let me know if I'm wrong.

thanks!
-john


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