>
> * Jason Wessel <jason.wessel@windriver.com> wrote:
>
> > > [...] The final initcall is init_kgdbts() and disabling KGDB
> > > prevents the hang.
>
>
> > That enables verbose logging of exactly what is going on and will show
> > where wheels fall off the cart. If the kernel is dying silently it
> > means the early exception code has completely failed in some way on
> > the kernel architecture that was selected, and of course the .config
> > is always useful in this case.
>
> incidentally, just today, in overnight testing i triggered a similar
> hang in the KGDB self-test:
>
>
http://redhat.com/~mingo/misc/config-Thu_Apr_17_23_46_36_CEST_2008.bad
>
> to get a similar tree to the one i tested, pick up sched-devel/latest
> from:
>
>
http://people.redhat.com/mingo/sched-devel.git/README
>
> pick up that failing .config, do 'make oldconfig' and accept all the
> defaults to get a comparable kernel to mine. (kgdb is embedded in
> sched-devel.git.)
>
> the hang was at:
>
> [ 12.504057] Calling initcall 0xffffffff80b800c1: init_kgdbts+0x0/0x1b()
> [ 12.511298] kgdb: Registered I/O driver kgdbts.
> [ 12.515062] kgdbts:RUN plant and detach test
> [ 12.520283] kgdbts:RUN sw breakpoint test
> [ 12.524651] kgdbts:RUN bad memory access test
> [ 12.529052] kgdbts:RUN singlestep breakpoint test
>
> full log:
>
>
http://redhat.com/~mingo/misc/log-Thu_Apr_17_23_46_36_CEST_2008.bad
>
> note that this was a 64-bit config too - our tests do a perfect mix of
> 50% 32-bit and 50% 64-bit kernels. So single-stepping of the kernel
> broke in some circumstances.
>
> find the boot log below. (it also includes all command line parameters)
>
> This is the first time ever i saw the self-test in KGDB hanging, so it's
> some recent non-KGDB change that provoked it or made it more likely. The
> KGDB self-test runs very frequently in my bootup tests:
>
> [ 12.508236] kgdb: Registered I/O driver kgdbts.
> [ 12.511245] kgdbts:RUN plant and detach test
> [ 12.517418] kgdbts:RUN sw breakpoint test
> [ 12.521056] kgdbts:RUN bad memory access test
> [ 12.525515] kgdbts:RUN singlestep breakpoint test
> [ 12.531483] kgdbts:RUN hw breakpoint test
> [ 12.536142] kgdbts:RUN hw write breakpoint test
> [ 12.541007] kgdbts:RUN access write breakpoint test
> [ 12.546223] kgdbts:RUN do_fork for 100 breakpoints
>
> so the latest kgdb-light tree literally survived thousands of such tests
> since it was changed last.
>
> unfortunately, the condition was not reproducible - i booted it once
> more and then it came up just fine - using the same bzImage.
>
> there's no recent change in x86.git related to the TF flag that i could
> think of to cause something like this. I checked changes to traps_64.c
> and entry_64.S, and nothing suspicious.
