Re: [PATCH 9/11] Panic delay fix

Dmitry Torokhov
2007-02-15T13:35:45Z

On 2/14/07, Rusty Russell <rusty@rustcorp.com.au> wrote:
> On Mon, 2007-02-05 at 19:53 -0800, Zachary Amsden wrote:
> > Failure to use real-time delay here causes the keyboard to become demonically
> > possessed in the event of a kernel crash, with wildly blinking lights and
> > unpredictable behavior. This has resulted in several injuries.
>
> The problem is the normal one when we introduce a new concept into the
> kernel; there are two kinds of udelay, and they've been conflated. The
> most common case is a delay for real hardware devices; this can be
> eliminated for paravirtualization. The other cases, the tiny minority,
> are visible delays (keyboard leds), not knowing if they're necessary
> (very early boot), and async events (other CPUs coming up): ie.
> everything else.
>

Just for the record - I believe that i8042 is fine as is now. The only
place where real delay needs to be enforced is panic.c - it should
call panic blink routine once every 1 ms.

--
Dmitry