[Cbe-oss-dev] [PATCH 3/3] spufs context switch - fix interrupt routing

[Luke Browning]

On Thu, 2008-04-24 at 12:04 +1000, Benjamin Herrenschmidt wrote:
> On Wed, 2008-04-23 at 22:42 -0300, Luke Browning wrote:
> > I assume back to back interrupts happen all the time.
> 
> Yes.
> 
> >   The difference in
> > this case is that we are re-routing interrupts within a few hundred
> > instructions of issuing the dma restart.
> 
> Yup.
> 
> >   I assume we context switched
> > the spu context while it was segment faulting which caused the dma
> > restart to be deferred to context restore code within a few instructions
> > of the spu interrupt rerouting.  I assume that the SLB was not reloaded
> > by the context switch code, so the two faults were regenerated.  
> 
> Depends, there are other scenario, but yeah, basically.
> 
> > > There should never be two hash misses unless there is a restart in
> > > between.
> > > 
> > 
> > Can you have a class 0 exception and a class 1 hash miss occur at the
> > same time?  If so, we still have the same issue.
> 
> A different one (issue) as these are separate handlers altogether and
> don't muck up with CSA fields etc...

Separate handlers, but they both mess with csa, so this is another
issue.

> 
> But yes, it would be possible.

Luke