[OpenBIOS] sparc32 trap recovery

[Tarl Neustaedter]

On 2013-Jun-19 10:44 , Bob Breuer wrote:
[...]
> So I fired up my SS-20 and did a little poking around to see how the
> SuperSparc-II behaves here.
>    * page not mapped: read/write = Data Access Exception
>    * sbus timeout: read = Data Access Exception, write = Level 15 int
>    * afterwards, SFSR will always be cleared to 0
>
> For cpeek/cpoke, OBP will catch the Access Exception and Access Error,
> but it won't catch the Unaligned Access or Level 15 int.

Yeah - on current generation sparcs, I/O write failures aren't notified 
until long after the instruction has gone past. That generally means 
that PIO write failures generally don't get reported at the OK prompt - 
they just get dropped invisibly.