[kdb] KDB makes Nehalem hang at early boot until key press

[Thomas Renninger]

On Friday 30 October 2009 14:32:22 Martin Hicks wrote:
> 
> On Fri, Oct 30, 2009 at 12:02:57PM +0200, Thomas Renninger wrote:
> > 
> > we currently have a problem with latest Intel CPUs/BIOSes:
> > If the machine gets booted it hangs in:
> > init/main.c:
> > kdb_init();
> 
> Is this problem only on the latest Nehalem CPUs/BIOSes?  Can we have
> more information about the machine?
It first appeared on an Intel NDA devel machine.
But now we also see this on a released Ciso Blade (which might be more
or less based on the Intel one? Could also be more general...).
So this gets more urgent.
 
> We're using KDB on many released and pre-release Nehalem machines with
> no problems.
> 
> > As soon as an irq via keyboard is triggered, the machine continues 
> > booting and everything is fine.
> > 
> > Is this known already? Can someone point me to a patch?
> > 
> > If not, is there a repo having the latest code, I could try
> > out whether the latest version works.
> 
> The latest code, against 2.6.31, is
> 
> git://oss.sgi.com/kdb/kdb.git

Thanks.

> > IMO something like the attached patch makes sense?
> > This fixes the problem with kdb=off (our default).
> > But I am anxious that kdb code could still get activitated somehow
> > and the machine might oops when trying to access not initialized
> > kdb structures? Could someone give an estimation how risky that
> > patch really is?
> 
> I'd really rather fix the underlying problem.  I have no idea what that
> might be though...
Me too...