Re: Periodic RTC interrupt

From: Ralf Baechle (ralf@uni-koblenz.de)
Date: Sun Feb 20 2000 - 12:21:57 EST


On Sun, Feb 20, 2000 at 02:07:16PM +0100, Guest section DW wrote:

> > > What application need the /dev/rtc periodic interrupt? I'm porting to
> > > a platoform which uses a M58T35 RTC which doesn't supply such an
> > > interrupt, so the question is if it's worth to care at all and possibly
> > > emulate an timer interrupt from another source.
> >
> > The RTC driver doesn't make much sense without interrupts...
>
> hwclock tries to use /dev/rtc to read and set the hardware clock.
>
> [Of course the idea is that if the kernel provides this access
> then a userspace program need not try to access the hardware itself.
> Today there are still machines where "hwclock --directisa" works
> but "hwclock" fails, so the kernel code for rtc is not perfect yet.]

I'd actually like to see --directisa support to be removed from hwclock or
at least to be a #ifdef __i386__. The last time I had to hack hwclock for
the n+1th MIPS port it was much more portable than it's predecessor clock
but the direct port accesses still make it somewhat messy.

What is the problem with /dev/rtc on those machines where hwclock fails?

  Ralf

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