Re: current kernel on amd64 crashes

[Andrew Doran <ad%netbsd.org@localhost>]

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.

Andrew