Re: [Linux-ia64] Exception handling and recovery

[Jack Steiner <steiner@sgi.com>]

> 
> On Tue, 12 Mar 2002 20:51:13 -0800, 
> David Mosberger <davidm@napali.hpl.hp.com> wrote:
> >>>>>> On Wed, 13 Mar 2002 14:53:31 +1100, Keith Owens <kaos@sgi.com> said:
> >
> >  Keith> Unlike i386, the ia64 exception table code only recovers from
> >  Keith> invalid user space addresses.  kdb can get other faults which
> >  Keith> EX() does not currently allow recovery from.  Is there any
> >  Keith> reason why I should not add exception table handling to
> >  Keith> ia64_fault(), to generalize the fault recovery mechanism?
> >
> >You mean kdb would do get_user() on a bad pointer, which triggers
> >ia64_fault() and then you want to search the exception table in
> >ia64_fault()?  I think it would be ok to do this (in the KDB patch).
> 
> Exactly.  IMHO ia64_fault should always search_exception_table(), even
> if kdb is not installed.  Other architectures use exception tables to
> detect if the hardware supports extra instructions, registers, MSR
> values etc., exception recovery should be general purpose.
> 

I may have missed the context of the question, but on IA64 if kdb 
makes a reference to a bad region 6 or 7 pointer, it may trigger an MCA.
MCAs are not recoverable via search_exception_table(). 



-- 
Thanks

Jack Steiner    (651-683-5302)   (vnet 233-5302)      steiner@sgi.com