em/amd64 on 6.0-RC1

[Danny Braniss]

I have been running this box (an Intel SR1435VP2/Xeon-NOCOMA), of which
we have 6, under several different configurations to try and pin down
some problems, initialy I suspected am-utils, but now it's almost certain
the if_em. The problem is sometimes on i386, but always on amd64.

it seems that the problem starts right after the em is re-initialized, after
it was used via PXE to boot. Sniffing shows that the kernel sends
a GETATTR, the server responds, but the client does not see it, and
after some time it will resend, and so on ...

pinging from the server to the client works.

btw, booting off the local disk (not diskless/PXE) em works fine, though
the logs seems a bit baffling:

	...
	em0: no link ... got link
	DHCPDISCOVER on em0 to 255.255.255.255 port 67 interval 3
	DHCPDISCOVER on em0 to 255.255.255.255 port 67 interval 8
	DHCPDISCOVER on em0 to 255.255.255.255 port 67 interval 9
	DHCPOFFER from 132.65.16.10
	unknown dhcp option value 0xfc
	DHCPREQUEST on em0 to 255.255.255.255 port 67
	DHCPACK from 132.65.16.10
	unknown dhcp option value 0xfc
	bound to 132.65.16.104 -- renewal in 7200 seconds.

	lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
 	       inet6 ::1 prefixlen 128 
  	      inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2 

	em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        	options=b<RXCSUM,TXCSUM,VLAN_MTU>
        	inet6 fe80::20e:cff:fe6a:8973%em0 prefixlen 64 scopeid 0x1 
        	inet 132.65.16.104 netmask 0xfffff000 broadcast 132.65.31.255
        	ether 00:0e:0c:6a:89:73
        	media: Ethernet autoselect
        	status: no carrier
	**************** HU? *************

later on, ifconfig em0 shows that all is ok.

danny