In case anybody's interested...

[Nicolas Souchu]

On Wed, Apr 09, 2003 at 04:41:29PM +1000, Bruce Evans wrote:
[...]
> Testing of lpt while debugging this showed other nice races: lpt
> (actually ppc) detaches and attaches the interrupt for every i/o.  It

Indeed for interrupt sharing. Actually, only lpt is used as a ppbus device.

> apparently doesn't wait long enough for the last (non-stray) interrupt
> from the previous i/o to arrive.  The interrupt sometimes arrives in
> the window between the detach and the attach.  It is then recorded as
> "stray".  It is stray all right, but "stray" was meant to mean stray
> in the hardware and not stray due to software bugs.

The interrupt certainly arrive between the the TEARDOWN and SETUP calls
in ppc_teardown_intr() of isa/ppc.c

-- 
Nicholas Souchu - nsouch at free.fr - nsouch at FreeBSD.org