On Wed, 2006-06-28 at 10:51 +0200, Jan Kiszka wrote:
> Philippe Gerum wrote:
> > On Wed, 2006-06-28 at 10:18 +0200, Jan Kiszka wrote:
> >> Philippe Gerum wrote:
> >>> On Wed, 2006-06-28 at 09:51 +0200, Jan Kiszka wrote:
> >>>> Philippe Gerum wrote:
> >>>>> On Mon, 2006-06-26 at 19:21 +0200, [EMAIL PROTECTED] wrote:
> >>>>>> plain text document attachment (enhance-kernel-fault-report.patch)
> >>>>>> Introduce xnarch_fault_um() to test if a fault happened in user-mode 
> >>>>>> and applies the new feature to report core and driver crashes more 
> >>>>>> verbosely. 
> >>>>>>        if (xnpod_shadow_p()) {
> >>>>>>  #ifdef CONFIG_XENO_OPT_DEBUG
> >>>>>> -              if (xnarch_fault_notify(fltinfo))       /* Don't report 
> >>>>>> debug traps */
> >>>>>> +              if (!xnarch_fault_um(fltinfo)) {
> >>>>>> +                      xnarch_trace_panic_freeze();
> >>>>> KGDB breakpoint issue?
> >>>> Sorry, please switch on verbose mode, didn't get yet what you mean.
> >>> Oops, sorry. I meant: what if a KGDB breakpoint is hit from kernel space
> >>> while running a shadow thread? The way I read the modified test sequence
> >>> above, such bp trap is going to trigger a panic, instead of being
> >>> silently passed to Linux.
> >> I would say: KGDB will not come along here with a breakpoint. It should
> >> already got involved in __ipipe_divert_exception().
> > 
> > Ok, so the only problem that remains would be inlined asm("int 1/3") in
> > kernel space not handled by KGDB (whether the KGDB patch is in or not).
> > I'm still scratching my head pondering if we can live with this or not.
> 
> But this is perfectly one of the situations my patch tries to catch: a
> fatal bug in the kernel! Such a hand-coded kernel breakpoint without a
> debugger caring is a bug to me.

Not that sure: passive debug code may exist. Only the presence of the
debugger should activate it.

> 
> Jan
> 
-- 
Philippe.



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