Re: [Xen-devel] Network drop on domU (netfront: rx->offset: 0, size: 4294967295)

[Dennis Krul <dweazle@xxxxxxxxx>]

Michael,

We've encountered the same problem. (We're using your packages btw, thanks for publishing them ;)

For what it's worth, you can work around the speed issue by disabling TCP segmentation offloading (ethtool -K ethX tso off). 
(You should disable it in your dom0 on all interfaces and in the domU as well.)

Unfortunately there is no apparent way to disable tso when kickstarting a domU, but other than that the speeds are back to normal.

Regards,
-- Dennis Krul <dweazle@xxxxxxxxx>

On Fri, May 29, 2009 at 12:02 AM, M A Young <m.a.young@xxxxxxxxxxxx> wrote:

I have started to see this error as well now on a Fedora Rawhide + xen-tip/next dom0 kernel on Fedora 11 and a Fedora 11 domU. The base system has just been reinstalled and used to be running Fedora 8 dom0, the domU machine hasn't changed. This is on a fairly old machine with 512M memory shared between the two instances.

/var/log/messages is packed with errors like
net eth0: rx->offset: 0, size: 4294967295
with the more occasional
__ratelimit: 25 callbacks suppressed
about every 10 lines, while updating some packages using rpm where the packages are on an NFS mount, which is maybe running at 1/10th or less the speed than I would expect. The network setup on dom0 is

bridge name     bridge id               STP enabled     interfaces
eth0            8000.0011110a766f       no              peth0
                                                       vif4.0

with only a handful of dropped packets on vif4.0
vif4.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
         inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
         UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
         RX packets:524716 errors:0 dropped:0 overruns:0 frame:0
         TX packets:658136 errors:0 dropped:39 overruns:0 carrier:0
         collisions:0 txqueuelen:32
         RX bytes:36703881 (35.0 MiB)  TX bytes:862875521 (822.9 MiB)

On domU however ifconfig reports
         UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
         RX packets:567462 errors:73814 dropped:0 overruns:0 frame:0
         TX packets:511318 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000
         RX bytes:719940314 (686.5 MiB)  TX bytes:42982009 (40.9 MiB)
         Interrupt:9

I tried enabling debugging in drivers/xen/netback/netback.c by setting
#define NETBE_DEBUG_INTERRUPT
but when I try to build the kernel I get the error
drivers/xen/blkback/xenbus.c: In function 'blkif_xenbus_init':
drivers/xen/blkback/xenbus.c:541: warning: ignoring return value of 'xenbus_register_backend', declared with attribute warn_unused_result
drivers/xen/netback/netback.c: In function 'netback_init':
drivers/xen/netback/netback.c:1503: error: 'SA_SHIRQ' undeclared (first use in this function)
drivers/xen/netback/netback.c:1503: error: (Each undeclared identifier is reported only once
drivers/xen/netback/netback.c:1503: error: for each function it appears in.)
drivers/xen/netback/netback.c:1505: warning: passing argument 3 of 'bind_virq_to_irqhandler' from incompatible pointer type

       Michael Young

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