Philippe Gerum wrote:
> 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.
> 

...but remains a bug for me /w RT code. We now complain about this
exception happened. And there is no crash/BUG in this case, just a
desirable warning with back-trace in the log.

Jan


PS: Other OSes show you a nice blue-screen when they ran on such
orphaned breakpoints.

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