On 2/14/07, Rusty Russell <[email protected]> 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
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