Re: kernel panic with pccard insert on recent 7.0 CURRENT

On Sunday 17 June 2007 01:56:59 am M. Warner Losh wrote:
> In message: <20070617053746.GV4602_at_funkthat.com>
>             John-Mark Gurney <gurney_j_at_resnet.uoregon.edu> writes:
> : Warner Losh wrote this message on Sat, Jun 16, 2007 at 21:12 -0600:
> : > In message: <20070617024935.GU4602_at_funkthat.com>
> : >             John-Mark Gurney <gurney_j_at_resnet.uoregon.edu> writes:
> : > : Warner Losh wrote this message on Sat, Jun 16, 2007 at 17:33 -0600:
> : > : > Also, I'm unclear on the difference between FILTER_STRAY and
> : > : > FILTER_HANDLED.
> : > : 
> : > : The interrupt filter is suppose to return one of FILTER_STRAY or
> : > : FILTER_HANDLED...  If you _HANDLED it return that, otherwise return
> : > : _STRAY...  If you need to schedule the ithread, return _HANDLED or'd
> : > : with _SCHEDULE_THREAD...
> : > 
> : > Will _HANDLED cause all the other handlers to not get called, or just
> : > the stray interrupt code from not happening?
> : 
> : It will cause the remaining (not yet called) handlers not to get called...
> 
> I'm not sure that's right, especially for edge triggered devices.\

They shouldn't share interrupts then.  Do we support shared interrupts on edge 
triggered devices?

> : intr_event_handle calls intr_filter_loop which will return on the first
> : non-_STRAY handler and return it...  Which intr_event_handle eoi's...
> :
> : It looks like this code is designed for level triggered interrupts and
> : not edge triggered...
> 
> Yes.  I'm pretty sure that's wrong.  All ISA and PC Card devices use
> edge triggered interrupts.  Also, it is inefficient for level
> triggered interrupts, since two interrupt sources on the same
> interrupt may trigger at about the same time...

It works fine since the second device will interrupt again and we will fall 
through to its routine on the second interrupt.  The idea is that 
simultaneous interrupts are rare enough that it is worth optimizing the 
common case.

-- 
John Baldwin