Date: Wed, 15 Jul 2015 00:54:25 -0700 From: Colin Percival <cperciva@freebsd.org> To: Kristof Provost <kp@FreeBSD.org>, Mark Felder <feld@FreeBSD.org> Cc: freebsd-xen@freebsd.org, gnn@freebsd.org Subject: Re: Networking under Xen Message-ID: <55A611B1.6000000@freebsd.org> In-Reply-To: <20F2398D-ECDF-4CF4-966D-18C894779C4C@FreeBSD.org> References: <4E7B7075-4E0D-4EA7-9F5D-6D252CFBD487@gmail.com> <1436890526.3162974.323521249.6B73E6E2@webmail.messagingengine.com> <55A55AE8.4090101@freebsd.org> <1436901780.3211878.323698017.360F8D73@webmail.messagingengine.com> <20F2398D-ECDF-4CF4-966D-18C894779C4C@FreeBSD.org>
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On 07/15/15 00:44, Kristof Provost wrote:=0D
>> On 14 Jul 2015, at 21:23, Mark Felder <feld@FreeBSD.org> wrote:=0D
>> On Tue, Jul 14, 2015, at 13:54, Colin Percival wrote:=0D
>>> More precisely *pf* is a known issue. It's inserting TCP checksums=0D
>>> into TSO packets. I reported this a long time ago and I don't know=0D
>>> why pf still hasn't been fixed.=0D
>>=0D
>> I think Kristof may have solved this in HEAD with all of the care and=0D
>> feeding he has been doing to pf, but I haven't verified.=0D
>=0D
> I wouldn=E2=80=99t expect so. As far as I know I=E2=80=99ve not fixed any=
thing TSO or=0D
> checksum related.=0D
=0D
In my tests, deleting these lines from pf_ioctl.c=0D
=0D
3570 /* We need a proper CSUM befor we start (s. OpenBSD ip_output) */=0D
3571 if ((*m)->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {=0D
3572 in_delayed_cksum(*m);=0D
3573 (*m)->m_pkthdr.csum_flags &=3D ~CSUM_DELAY_DATA;=0D
3574 }=0D
=0D
unbreaks pf+TSO on EC2 instances. I'm not entirely sure why these lines=0D
are there in the first place, which is why I didn't want to simply go in=0D
and remove them -- but it may be that wrapping those lines in something=0D
like "if ((csum_flags & CSUM_TSO) =3D=3D 0)" would solve the problem withou=
t=0D
breaking anything else.=0D
=0D
-- =0D
Colin Percival=0D
Security Officer Emeritus, FreeBSD | The power to serve=0D
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid
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