Re: [Xenomai-core] [PATCH 2/6] Improve fault report

[Jan Kiszka <jan.kiszka@domain.hid>]

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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, jan.kiszka@domain.hid 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.

Jan


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