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

H. Peter Anvin
2006-07-25T20:26:46Z

Dave Airlie wrote:
>
> So far the requirements are pretty much not high resolution but is
> accurate and increasing. so like 10ms is fine, the current X timer is
> in the 20ms range.
>
> I think an mmap'ed page with whatever cgt(CLOCK_MONOTONIC) returns
> would be very good, but it might be nice to implement some sort of new
> generic /dev that X can mmap and each arch can do what they want in
> it,
>
> I'm wondering why x86 doesn't have gettimeofday vDSO (does x86 have
> proper vDSO support at all apart from sysenter?),
>

The i386 vdso right now has only two entry points, as far as I can tell:
system call and signal return.

There is no reason it couldn't have more than that. A low-resolution
and a high-resolution gettimeofday might be a good idea.

-hpa