Re: [PATCH 9/11] Panic delay fix

Andi Kleen
2007-02-08T13:33:23Z

On Thu, Feb 08, 2007 at 01:08:14AM -0800, Zachary Amsden wrote:
> Andi Kleen wrote:
> >On Wed, Feb 07, 2007 at 02:31:57PM -0800, Zachary Amsden wrote:
> >
> >>Dmitry Torokhov wrote:
> >>
> >>>I am confused - does i8042 talk to a virtual or real hardware here? In
> >>>any case I think you need to fix kernel/panic.c to have proper
> >>>(m)delay, not mess with i8042.
> >>>
> >>I think I need to fix both of them actually. This is virtual hardware,
> >>but when you grab focus on a VM, the virtual hardware gets reflected to
> >>the actual physical keyboard. Driving physical hardware that fast is bad.
> >>
> >
> >???
> >
> >Surely the physical keyboard is always handled by the host kernel?
> >I hope you're not saying it's trying to access the io ports directly?
> >
>
> No, not that. But the virtual keyboard I/O gets processed and converted
> to physical keyboard I/O when a keyboard is attached to a VM. The

You mean the commands to change the keyboard LEDs?

> result is that the virtual keyboard spinning out of control causes the
> physical keyboard to receive the same commands, far too rapidly.

Hmm i would expect the host kernel keyboard driver to throttle these.
I'm pretty sure the Linux one does the necessary mdelays at least.

> So the keyboard blinks out of control and acts as if possessed by demons.

Still sounds weird.

-Andi