Re: [2.6.27] early exception - lockdep related?

[Peter Zijlstra <peterz@infradead.org>]

On Wed, 2008-09-03 at 21:21 +0200, Luca Tettamanti wrote:
> On Wed, Sep 3, 2008 at 10:28 AM, Luca Tettamanti <kronos.it@gmail.com> wrote:
> > On Wed, Sep 3, 2008 at 8:52 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> >> On Tue, 2008-09-02 at 23:06 +0200, Luca Tettamanti wrote:
> >>> Hello,
> >>> I'm seeing an early exception (0e) - which seems related to lockdep - at
> >>> boot with many 2.6.27 kernels and I'm having troubles to track it down.
> >>
> >> Does it print one of these nice stack traces?
> >
> > Of course not ;-) It dies before dumping the stack trace (or at least
> > it doesn't make to the console - that machine has a serial port, but
> > my notebook does not... I've ordered a usb-to-serial adapter).
> >
> >>> The strange thing is that it comes and goes with different kernel
> >>> versions
> >>
> >> What kernel version did you generate the below with - and what config.
> >
> > -rc2 is working, after that it's intermittent. The last kernel that I
> > tried is -git from a couple of days ago.
> >
> >>> , but a "bad" kernel consistently fails across reboots. It also
> >>> seems to be sensitive to the configuration (attached)
> >>
> >> you seem to have forgotten that attachment.
> >
> > Ops, will send as soon as I get home.
> 
> Config is attached.
> 
> I tried netconsole, but got not output. No luck with qemu either :S
> 
> QEMU from SVN reports that:
> qemu: fatal: Trying to execute code outside RAM or ROM at 0x00000000000a0000
> 
> KVM goes a bit further but dies due to an exception while the kernel
> is still executing in real mode.

Sadly your config just boots, albeit not to userspace due to missing
drivers.

root@twins:/mnt/build/linux-2.6# git-describe
v2.6.27-rc5-6-gbef69ea

root@twins:/mnt/build/linux-2.6# /mnt/md0/cross/bin/x86_64-linux-gcc --version
x86_64-linux-gcc (GCC) 4.3.1 20080510 (prerelease)