Re: /dev/rtc on alpha

[Bob McElrath <bob+linux-kernel@mcelrath.org>]

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Ivan Kokshaysky [ink@jurassic.park.msu.ru] wrote:
> On Sat, Nov 08, 2003 at 01:33:57PM -0800, Bob McElrath wrote:
> > Why is the alpha kernel code grabbing the rtc interrupt?  Is it possible
> > it share its use with a user program?  Would reprogramming the interrupt
> > rate by a user program do violence to some internel kernel timing?
> 
> On most Alphas RTC is the system timer (running at 1024 Hz).
> So changing the interrupt rate from user space wouldn't be a good idea.

Then I propose CONFIG_RTC be set to "n" in the arch/alpha files, and the
/dev/rtc driver be disabled on alpha.  There seems to be confusion on
this point in the config files.  CONFIG_RTC is for the /dev/rtc driver.

Since the timer can only be set to powers of 2, it should be possible to
simulate getting the interrupt by calling the rtc.c interrupt handler
every 2^n interrupts...that way the user could program the timer for any
interval less than 1024 Hz.

Cheers,
Bob McElrath [Univ. of California at Davis, Department of Physics]

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