Subject: Re: NetBSD crashes on 4 GB Supermicro
To: Brian Marcotte <>
From: Manuel Bouyer <>
List: port-xen
Date: 05/04/2007 15:04:12
On Thu, May 03, 2007 at 07:33:44PM -0400, Brian Marcotte wrote:
> > build a XEN3_DOMU kernel with -g and boot it. Then use gdb netbsd.gdb
> I remember why I rarely use gdb.
> I think it looks like this (3.1 sources):
>   locore.S:456            start
>   xen_machdep.c:422       xpmap_init
>   xen_machdep.c:311       xpmap_get_bootpte (crashed here)
> xpmap_get_bootpte may have called these before crashing:
> 	xpmap_get_bootptep
> 	  xpmap_get_vbootpde
> 	    xpmap_get_bootpde
> 	    xpmap_mtop
> I can't tell by just looking at the code if this is NetBSD's fault or
> Xen's.
> Is there a way to single step a running kernel under xen,

I fear it's not possible at this point; not enough things have been
set up to use ddb

> or do I
> need to do some sort of printf thing? Which would I use (XENPRINTF,
> XENPRINTK, etc. )?

printf() won't work either; but I suspect printk (XENPRINTK) may (this
will show up on xen's console, not the domU console).
You'll need a DEBUG xen,gz for this; but when building you'll have
to disable NDEBUG manually (I don't have the sources handy to tell you
where, sorry) because for debug xen uses one of the free PTE bits that
NetBSD use too.

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference