unpredictable Xen crash w NetBSD 5.0.2(XEN3PAE_DOMU)

[å <sukinull%gmail.com@localhost>]

Dear all:

I'm sorry I crossmail.

I try setup aoe-vblade server on netbsd 5.0.2(domU)
and I try to do some stress test with
for i in {65536}; do dd if=/dev/zero of=/dev/etherd/e?.? bs=4K;done
on a Linux box
Two Xen dom0 configurations I use:
1. 32bits SuSE Enterprise Linux 11sp1 2.6.32.12-0.7-xen with 32bits
Xen 4.0.0_21091_04-0.2.6
2. 64bits Gentoo 2.6.32-xen-r1 with 64bits Xen 4.0.0
The NIC is RTL-8169 on board

After 20~40mins later, whole system (include dom0 and Xen) will crash
and reboot.
xm dmesg
dmesg
system message log
xend.log
console
output nothing at crash

However if I replace NetBSD with FreeBSD 8.0p2 and SuSE JeOS 11.3
the stress test is stable (~6hours).

Can anyone give me sugguestions to figure out what's the problem?
Thank you

Angelo Liaw