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Re: current kernel on amd64 crashes
On Sat, Jan 12, 2008 at 07:18:00AM +0000, David Laight wrote:
> On Fri, Jan 11, 2008 at 08:35:43PM +0100, Joerg Sonnenberger wrote:
> > On Thu, Jan 10, 2008 at 08:41:35PM +0000, David Laight wrote:
> > > > Could it be this change ?
> > > > - low = inb(IO_TIMER1 + TIMER_CNTR0);
> > > > - high = inb(IO_TIMER1 + TIMER_CNTR0);
> > > > - count = rtclock_tval - ((high << 8) | low);
> > > > -
> > > > + /* insb to make the read atomic */
> > > > + insb(IO_TIMER1+TIMER_CNTR0, &rdval, 2);
> > > > + count = rtclock_tval - rdval;
> > >
> > > I don't know, but I also have no reason to believe that the comment (and
> > > hence the modified code) is correct.
> > The only real diff is that you won't get interrupts processed in the
> > middle, I think.
> You think incorrectly :-) the x86 'rep' instructions are interruptable
> between the iterations.
I don't know what I was thinking when I changed that bit of code but it's
wrong, the two inb() calls are correct. I'll see about changing it back.
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