7.0 RC2 kernel panic with Kqemu/AMD64

Juergen Lock nox at jelal.kn-bremen.de
Sat Feb 16 21:08:47 UTC 2008

On Sat, Feb 16, 2008 at 08:10:35PM +0100, MFL Commissioner wrote:
> Juergen,
> I would be happy to help debug this, although someone would have to give me 
> step by step instructions on what to do exactly.
> This is a development machine that (roughly) mirrors a production setup, so 
> I have maintain the SMP/AMD64 configuration.
> What I am still not quite clear on is this:  Is this a Qemu problem or 
> FreeBSD kernel problem?

I guess its a kqemu problem that only shows up on FreeBSD, or a combination
of issues in kqemu and the FreeBSD kernel, but as I said the actual cause
of the problem is still unknown...
> Anyway, I'll do what you ask to provide you with my backtraces, but I doubt 
> that I will be able to interpret the results.

 OK, I guess you want to start here:

 And of course you want to build a debug kernel (makeoptions     DEBUG=-g),
building a kernel is explained here:

 I also had to put DDB into the kernel so that it gets built without
-fomit-frame-pointer (you probably want KDB_UNATTENDED then too, and
KDB_TRACE while you're at it.)

 Oh and I guess you want to disable minidumps also (sysctl debug.minidump=0),
there's a race in there that might(!) cause not so useful dumps otherwise.

 Then when you have a dump, post a script(1) of a `bt' in kgdb, and we'll
see if it tells more than the backtraces I got...


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