Re: Core Exception Throwing and Handling

[Andrew Cagney <cagney at redhat dot com>]

Phil Muldoon wrote:
> I thought I'd start this conversation going. It's been an action item 
> for awhile.
There are two issues here, and I think it is important to consider each 
separately:

1) the first is a core panic, which from the UI point-of-view is 
asynchronous and fatal
The only technical point worth debating here is how to get the core to 
cleanly extract itself from the tasks it;s controlling; and perhaps 
should the core be started a-new.

2) a failure during a synchronous I/O operation (such as fetch a 
register) which could either be a table-lookup failure or (rarely) 
kernel spontaneously disappeared a task

I gather it is the second one that is of concern here.  While more 
meaningful exceptions would be useful here, for the specific case at 
hand I think, as Yao pointed out, that the correct thing is to _not_ 
throw an exception.  A target program having a bogus syscall num should 
not lead to any exception being thrown - from frysk's point-of-view a 
bogus syscall num is just as valid as a correct num.

Andrew