Re: [Xen-users] DNAT TCP checksum error

[Jason <xen@xxxxxxxxxxxxxxxxx>]

Im not an expert on this either, I have just had to deal with it myself very 
recently.  A post went out on the devel list earlier
talking about theoretical reasons as to why the tcpchecksum code is disabled 
for virtual interfaces.  I have posed the question back to
the devel list asking for a clarification as to why that is done and if it 
could just be removed since it seems to impact a lot of
people (everyone that isn't bridging as far as I can tell). 
As for fixing it in the kernel, you can edit the file drivers/xen/netback/interface.c  .   look for the line 
dev->features        = NETIF_F_NO_CSUM;
and replace it with

dev->features        = 0; /*NETIF_F_NO_CSUM; */


which as I understand it will re-enable checksums at the virtual interface 
level and worked very well for me.  If I hear something back on why this code 
is set to
disable checksums, I will post it to here.

--
Jason
The place where you made your stand never mattered,
only that you were there... and still on your feet

On Sat, 1 Apr 2006, Javier Guerra wrote:

> On Saturday 01 April 2006 1:15 pm, jean-luc.voisin wrote:
> > the "ethtool -K eth0 tx off" corrects the problem, but how to solve the
> > problem within the kernel ?
> i don't understand fully why this is sometimes needed.  does it makes the
> driver not to write checksums? or not to rely on hardware checksumming?
_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users