Re: [PATCH] Re: time() glitch on 2.4.18: solved

[george anzinger <george@mvista.com>]

Jim Paris wrote:
> 
> > > Any comments?
> >
> > Have a play with it, if your idea works when you deliberately disturb it
> > then send in a patch
> 
> This works well.

But it does introduce a hiccup in time.  One could just do
an odd read IF that is all that is wrong.  Your code could
also be correcting for other ills...

-g
> 
> -jim
> 
> diff -urN linux-2.4.18/arch/i386/kernel/time.c linux-2.4.18-jim/arch/i386/kernel/time.c
> --- linux-2.4.18/arch/i386/kernel/time.c        Fri Mar 15 18:28:53 2002
> +++ linux-2.4.18-jim/arch/i386/kernel/time.c    Tue Nov  5 11:22:02 2002
> @@ -501,6 +501,16 @@
> 
>                 count = inb_p(0x40);    /* read the latched count */
>                 count |= inb(0x40) << 8;
> +
> +               /* Any unpaired read will cause the above to swap MSB/LSB
> +                  forever.  Try to detect this and reset the counter. */
> +               if (count > LATCH) {
> +                       outb_p(0x34, 0x43);
> +                       outb_p(LATCH & 0xff, 0x40);
> +                       outb(LATCH >> 8, 0x40);
> +                       count = LATCH - 1;
> +               }
> +
>                 spin_unlock(&i8253_lock);
> 
>                 count = ((LATCH-1) - count) * TICK_SIZE;
> -
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-- 
George Anzinger   george@mvista.com
High-res-timers: 
http://sourceforge.net/projects/high-res-timers/
Preemption patch:
http://www.kernel.org/pub/linux/kernel/people/rml