checksum/tso offload makes packets vanish on wm in bridge?

[Thor Simon <tls%coyotepoint.com@localhost>]

It appears that if I do this:

ifconfig wm0 10.0.0.2/24
ifconfig bridge0 create
ifconfig bridge0 add wm0

Everything works as expected: I can, for example, ping 10.0.0.1.

However, if I then do this:

ifconfig wm0 ip4csum tcp4csum udp4csum tso4

frames disappear without being output: tcpdump doesn't even show my
icmp echo frames on wm0 at all, and I don't get echo replies.

With ip4csum, tcp4csum, udp4csum tso4 on but no bridge configured,
all works as expected.

Has anyone else seen this?  Does anyone have any idea why it might be
happening?  The host is running amd64 5.0_RC1 under Xen 3.3.

-- 
Thor Lancelot Simon
Coyote Point Systems, Inc.                      <tls%coyotepoint.com@localhost>
Millerton, NY, USA