From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [Xenomai-core] [PATCH 2/6] Improve fault report From: Philippe Gerum In-Reply-To: <44A24308.70703@domain.hid> References: <20060626172116.019532000@domain.hid> <20060626172118.347530000@domain.hid> <1151480559.5154.2.camel@domain.hid> <44A234F9.9010705@domain.hid> <1151481889.5154.14.camel@domain.hid> <44A23B66.7070202@domain.hid> <1151483788.5154.22.camel@domain.hid> <44A24308.70703@domain.hid> Content-Type: text/plain Date: Wed, 28 Jun 2006 11:00:07 +0200 Message-Id: <1151485207.5154.28.camel@domain.hid> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Reply-To: rpm@xenomai.org List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: xenomai@xenomai.org 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, 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. Not that sure: passive debug code may exist. Only the presence of the debugger should activate it. > > Jan > -- Philippe.