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Date:      Wed, 22 Jul 2015 16:04:24 +0300
From:      Pavel Timofeev <timp87@gmail.com>
To:        Wei Hu <weh@microsoft.com>
Cc:        Slawa Olhovchenkov <slw@zxy.spb.ru>,  "freebsd-current@freebsd.org" <freebsd-current@freebsd.org>,  "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org>
Subject:   Re: MS DNS doesn't answer to CURRENT under Hyper-V
Message-ID:  <CAAoTqftfJbcaHFUeAEYnFpNqhVvyqE=BUwJbE6BSEJ_PEQ9Dwg@mail.gmail.com>
In-Reply-To: <BY1PR03MB1434AB3E1C8F2D66BDE1AB2CBB9C0@BY1PR03MB1434.namprd03.prod.outlook.com>
References:  <CAAoTqftvtQunx%2BWCL4%2BBz-mYSgqCTcGx1aAyemfaz%2B=0ogZuWw@mail.gmail.com> <20150707130902.GA41189@zxy.spb.ru> <CAAoTqfsUfdAP1G=U4eDg3hfmuHtoosgGjOd9gMrehX%2BrcxaiJw@mail.gmail.com> <20150707154906.GA44094@zxy.spb.ru> <CAAoTqft_u1YEOGf6pThhHd-JuYoGnxzQxFpo-57SCUJ0OksWGw@mail.gmail.com> <BY1PR03MB1434AB3E1C8F2D66BDE1AB2CBB9C0@BY1PR03MB1434.namprd03.prod.outlook.com>

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Hi! I see you have done the code for disabling UDP checksum offloading
when running on the Hyper-V on Windows Server 2012 and earlier hosts

https://svnweb.freebsd.org/base?view=3Drevision&revision=3D285785

I tried new CURRENT and it works. Thank you!

A small note here: while it disables and works it still shows RXCSUM
and TSCSUM in iface's options:

root@proxy:/usr/src # ifconfig hn0
hn0: flags=3D8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=3D31b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,TSO4,TSO6>
        ether 00:15:5d:02:9c:09
        inet 192.168.25.26 netmask 0xffffffc0 broadcast 192.168.25.63
        nd6 options=3D29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>

Is it possible to hide it automatically if it's disabled by new code?


2015-07-13 11:06 GMT+03:00 Wei Hu <weh@microsoft.com>:
> We have root caused the problem. This issue happens on the Hyper-Vs on Wi=
ndows Server 2012 (Win 8.0) and earlier releases. On these releases, the UP=
D checksum offloading on host side does not work properly. The workaround i=
s to disable UPD checksum offloading in the FreeBSD guest through 'ifconfig=
'. We are also working on a patch to turn off UPD checksum offloading in th=
e netvsc driver when detecting the Hyper-V releases.
>
> The UDP checksum offloading works fine on Windows Server 2012R2 and Win 8=
.1 hosts.
>
> Thanks Pavel and Slawa for the support.
>
> Wei
>
>
>> -----Original Message-----
>> From: owner-freebsd-virtualization@freebsd.org [mailto:owner-freebsd-
>> virtualization@freebsd.org] On Behalf Of Pavel Timofeev
>> Sent: Wednesday, July 8, 2015 4:06 PM
>> To: Slawa Olhovchenkov
>> Cc: freebsd-current@freebsd.org; freebsd-virtualization@freebsd.org
>> Subject: Re: MS DNS doesn't answer to CURRENT under Hyper-V
>>
>> Ok, r284746 is the root of the problem. MS DNS works under r284745 and
>> doesn't work under r284746.
>> Slawa, what should I look at in wireshark output?
>>
>>
>> 2015-07-07 18:49 GMT+03:00 Slawa Olhovchenkov <slw@zxy.spb.ru>:
>> > On Tue, Jul 07, 2015 at 06:04:46PM +0300, Pavel Timofeev wrote:
>> >
>> >> Well, turning off checksum offloading by `ifconfig hn0 -txcsum
>> >> -rxcsum` definitely helps.
>> >>
>> >> As for tcpdump I'm not completely sure if I did it right, but I see
>> >> "bad udp cksum" phrase:
>> >>
>> >> # tcpdump -i hn0 -vvv -nn udp dst port 53
>> >> tcpdump: listening on hn0, link-type EN10MB (Ethernet), capture size
>> >> 262144 bytes
>> >> 18:01:19.139994 IP (tos 0x0, ttl 64, id 61218, offset 0, flags
>> >> [none], proto UDP (17), length 51)
>> >>     192.168.25.26.45683 > 192.168.25.3.53: [bad udp cksum 0xb39e ->
>> >> 0xf210!] 52886+ A? ya.ru. (23)
>> >> 18:01:24.140544 IP (tos 0x0, ttl 64, id 17293, offset 0, flags
>> >> [none], proto UDP (17), length 51)
>> >>     192.168.25.26.12575 > 192.168.25.3.53: [bad udp cksum 0xb39e ->
>> >> 0x7365!] 52886+ A? ya.ru. (23)
>> >
>> > tcpdump "bad udp cksum" is normal on FreeBSD host in case checksum
>> > offload (and may be need only for help finding issuse in code). Need
>> > wireshark capturing from MS DNS host (or from mirroring port).
>> _______________________________________________
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>> http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization
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