hangup (livelock) - db> prompt in endless loop

[Alexey Shuvaev]

On Wed, Dec 17, 2008 at 03:12:40PM +0100, Paul B. Mahol wrote:
> On 12/17/08, Alexey Shuvaev <shuvaev at physik.uni-wuerzburg.de> wrote:
> > On Tue, Dec 16, 2008 at 06:11:34PM +0300, Anton Yuzhaninov wrote:
> >> My box with fresh current sometimes stops to respond.
> >>
> >> On screen in endless loop printed debugger prompt
> >>
> >> db>
> >>
> >> but I can't type anything here.
> >>
> >> Alt+Ctrl+Esc and Alt+Ctrl+Del don't stops this loop.
> >>
> >> How I can debug this problem?
> >>
> >> system: current from Mon Dec 15 16:16:23 MSK 2008 with GENERIC kernel,
> >> amd64, SMP.
> >>
> > Me too!
> >
> > The system is:
> > # uname -a
> > FreeBSD wep4035 8.0-CURRENT FreeBSD 8.0-CURRENT #0: Mon Dec 15 14:21:48 CET
> > 2008
> >      root at wep4035:/usr/obj/usr/src/sys/USB2  amd64
> >
> > It can hang even in single user mode with only / mounted read-only,
> > but with already configured network (msk). I have never seen how it
> > happens, however :(
> 
> Looks like syscons problem, does it happen with kern.smp.disabled=1?
> 
I don't see it yet for
FreeBSD wep4035 8.0-CURRENT FreeBSD 8.0-CURRENT #0: Tue Dec 16 18:47:56 CET 2008     root at wep4035:/usr/obj/usr/src/sys/USB2  amd64

With 15 Dec current it should already be hanging.

Alexey.