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

H. Peter Anvin
2006-07-26T00:37:57Z

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