re(4) incorrect checksum

[Kris Kennaway]

On Thu, Jan 11, 2007 at 04:37:05PM +0100, Rene Ladan wrote:
> Pyun YongHyeon schreef:
> > On Thu, Jan 11, 2007 at 12:14:34PM +0100, Rene Ladan wrote:
> >  > Pietro Cerutti schreef:
> >  > > Hi lists,
> >  > > 
> >  > > FreeBSD gahrtop.localhost 6.2-PRERELEASE FreeBSD 6.2-PRERELEASE #1:
> >  > > Tue Jan  9 19:34:13 CET 2007
> >  > > root at gahrtop:/usr/obj/usr/src/sys/GAHRTOP  i386
> >  > > 
> >  > > CPU: Intel(R) Core(TM)2 CPU         T7200  @ 2.00GHz (2000.15-MHz
> >  > > 686-class CPU)
> >  > >  Cores per package: 2
> >  > > 
> >  > > re0: <RealTek 8168B/8111B PCIe Gigabit Ethernet> port 0xc800-0xc8ff
> >  > > mem 0xff2ff000-0xff2fffff irq 17 at device 0.0 on pci2
> >  > > 
> >  > > ($FreeBSD: src/sys/dev/re/if_re.c,v 1.46.2.20 2006/09/21 11:08:28
> >  > > yongari Exp $)
> >  > > 
> >  > > I get checksum errors on every packet I send, example:
> >  > > 
> >  > > Checksum: 0x0bc5 [incorrect, should be 0x78fe (maybe caused by
> >  > > checksum offloading?)]
> >  > > 
> >  > > I think this could be the cause of some web pages (e.g. Gmail in
> >  > > standard view [html view works well]) not to be displayed.
> >  > > 
> >  > > I tracked down the problem to the re(4) driver just because wlan works
> >  > > good...
> >  > > 
> >  > > Any ideas?
> >  > > 
> >  > I'm also seeing these www problems with my re(4) card (chipid
> >  > 0x816810ec), see
> >  > http://lists.freebsd.org/pipermail/freebsd-current/2006-December/068333.html
> >  > 
> > 
> > Does your re(4) also work when you disable checksum offload?
> > 
> Yes, 'ifconfig re0 -txcsum' does the trick.
> 
> re0: <RealTek 8168/8111B PCIe Gigabit Ethernet> port 0xc800-0xc8ff mem
> 0xfe0ff000-0xfe0fffff irq 16 at device 0.0 on pci2
> 
> if.re.c revision 1.80 2006/12/20 02:13:59 marius

Can you confirm that you see checksum errors when viewing the packet
from another host on the subnet?

It's of course to be expected that a sending host with checksum
offload on the NIC will not see the correct checksum before offloading
the packet to the NIC, and this in itself does not indicate a problem.

Kris
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