From: Andi Kleen <ak@suse.de>
To: john stultz <johnstul@us.ibm.com>
Subject: Re: [RFC][PATCH 1/6] x86_64: Enable arch-generic vsyscall support.
Date: Wed, 9 Aug 2006 04:59:05 +0200
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On Wednesday 09 August 2006 04:56, john stultz wrote:
> On Wed, 2006-08-09 at 04:29 +0200, Andi Kleen wrote:
> > > diff --git a/kernel/timer.c b/kernel/timer.c
> > > index b650f04..08b4a02 100644
> > > --- a/kernel/timer.c
> > > +++ b/kernel/timer.c
> > > @@ -1023,6 +1023,12 @@ static int __init timekeeping_init_devic
> > >  
> > >  device_initcall(timekeeping_init_device);
> > >  
> > > +#ifdef CONFIG_GENERIC_TIME_VSYSCALL
> > > +extern void update_vsyscall(struct timespec* ts, struct clocksource* c);
> > > +#else
> > > +#define update_vsyscall(now, c)
> > > +#endif
> > 
> > Using a weak dummy function would be a bit cleaner.
> 
> Will compilers optimize out the call properly?

No, but it's just a call ; ret then.

> 
> Looking at it now, it probably should go in a .h file and the empty
> define should be a proper "do { } while(0)" 

Or use weak

-Andi

 
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