em(4): sending ARP regardless of NOARP flag

[Xin LI]

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Hi, Jack,

I have observed that, even if -arp is specified when adding an IP
address to the em(4) interface, an ARP request is still being sent.
Here is a tcpdump from my network environment:

11:15:01.370256 00:13:72:66:b5:d7 > ff:ff:ff:ff:ff:ff, ethertype ARP
(0x0806), length 60: Request who-has *.*.152.120 tell *.*.152.120, length 46
11:15:01.370270 00:15:17:92:39:0e > 00:13:72:66:b5:d7, ethertype ARP
(0x0806), length 42: Reply *.*.152.120 is-at 00:00:5e:00:01:07, length 28

(The first ARP request was sent from a Dell branded Intel 82541EI based
NIC, the latter is from a cheaper server that is part of CARP
configuration which is unrelated to the problem in response to the ARP
request)

I was originally under the impression that there is some bug in our ARP
code but with a bce(4) card, the problem does not exist.  After a glance
at e1000 driver code, it looks like that the e1000 NIC has a feature of
hardware interception of ARP, can this be somehow connected?  The
hardware in question is 82541EI based:

em1 at pci0:7:8:0:	class=0x020000 card=0x016d1028 chip=0x10768086 rev=0x05
hdr=0x00
    vendor     = 'Intel Corporation'
    device     = '82541EI Gigabit Ethernet Controller'
    class      = network
    subclass   = ethernet

Thanks in advance!

Cheers,
- --
Xin LI <delphij at delphij.net>	http://www.delphij.net/
FreeBSD - The Power to Serve!
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