Two DOMU's hang on amd64 NetBSD 5.0_STABLE (XEN3_DOM0)

[Makoto Fujiwara <makoto%ki.nu@localhost>]

Hi, 
 I have NetBSD/amd64 5.0_STABLE DOM0 running. 

| modena@makoto 12:07:50/100509(..etc/xen)% uname -a
| NetBSD modena 5.0_STABLE NetBSD 5.0_STABLE (XEN3_DOM0) #0: 
| Wed Apr 7 02:17:52 UTC 2010 
| 
builds%b8.netbsd.org@localhost:/home/builds/ab/netbsd-5/amd64/201004070000Z-obj/
|    home/builds/ab/netbsd-5/src/sys/arch/amd64/compile/XEN3_DOM0
| amd64

| modena@makoto 12:32:46/100509(~)% pkg_info|grep xen
| xentools33-3.3.2nb2 Userland Tools for Xen 3.3.x
| xenkernel33-3.3.2   Xen 3.3.2 Kernel

And both (1) i386/5.0_STABLE and (2) i386/5.99.27 DOMU are running fine
when only one of those two is 'xm create'd.
But at the time when disk access on either side, all the
activity locks. DOM0 hangs. I needed power cycle to get DOM0 get
back.

When I say disk access, for example, meaning when one is running,
INSTALLer kernel starts fine on the other side. But once sysinst
needs writing to xbd0, everythings locks. (sometimes before that ?)

xen configurations are as follows:

modena@makoto 12:07:41/100509(..etc/xen)% head -20 disk-[gh]
==> disk-g <==
#ernel  = "/export/xen/kernel/head/netbsd-XEN3PAE_DOMU.gz"
kernel  = "/export/xen/kernel/head/netbsd-INSTALL_XEN3PAE_DOMU.gz"
memory  = 512
name    = "netbsd-HEAD"
disk    = [     'phy:/dev/wd1g,0x1,w']
vif     = [ 'mac=00:16:3e:02:00:37,bridge=bridge0' ]
root    = "xbd0"
pae     = 1

==> disk-h <==
#ernel  = "/export/xen/kernel/netbsd-5/netbsd-INSTALL_XEN3PAE_DOMU.gz"
kernel  = "/export/xen/kernel/netbsd-5/netbsd-XEN3PAE_DOMU.gz"
memory  = 1024
name    = "netbsd-5.0_STABLE"
disk    = [     'phy:/dev/wd1h,0x1,w']
vif     = [ 'mac=00:16:3e:02:00:38,bridge=bridge0' ]
root    = "xbd0"
pae     = 1
modena@makoto 12:07:50/100509(..etc/xen)% 

I am doing very much similar thing on NetBSD/i386 DOM0. I have
more than 4 DOMU's on that. 

So, There should be something wrong on my setup on amd64 or, 
some problem on amd64/xen.

Does anybody know what is wrong ?
Thanks for advices, in advance,
---
Makoto Fujiwara