Re: [PATCH] RTC: Add mmap method to rtc character driver

[H. Peter Anvin]

Neil Horman wrote:
> > > >
> > > It there any arch for which the rtc driver doesn't function?
> > Yes, there are plenty of systems which don't have an RTC, or have an RTC 
> > which can't generate interrupts.
> Ok, for those implementations which don't have an RTC that the rtc driver can
> drive, the mmap functionality will not work, but at that point what interface
> are you left with at all for obtaining periodic time?

Depends completely on the hardware.  Some hardware will rely on cycle 
counters, some may rely on I/O devices which may or may not be mappable 
into user space, and some will have to enter the kernel.

These aren't compatible with your programming model.

	-hpa
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