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SubjectRe: [RFC] Reentrant clock sources
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On Wed, 2008-11-26 at 04:07 +0100, Ingo Molnar wrote:
> * Thomas Gleixner <tglx@linutronix.de> wrote:
>
> > > + cycle_t (*vread)(struct clocksource *cs);
> >
> > This is crap. vread can not access the clocksource.
>
> i think 'reentrant' in the sense of creating self-sufficient driver
> entities. vread wont (and shouldnt) call ->vread() recursively - but
> it might want to access fields on the clocksource.

I think Thomas' issue is that vread() *cannot* access fields on the
clocksource (since vread has to be careful not to access any
non-vsyscall mapped memory).

However not all clocksources use vread(), but really I'm not quite clear
on what one would want to access in the clocksource structure when
making a ->read() call.

So maybe a further description of what specific need motivates this
change would be helpful? The brief description of power management
doesn't quite click in my head yet.

thanks
-john



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