[ovs-dev] [PATCH] xenserver: Fix ip_gre_mod modprobe issue in init script

Jesse Gross jesse at nicira.com
Tue Apr 13 15:06:01 UTC 2010

On Tue, Apr 13, 2010 at 5:36 AM, Ian Campbell <Ian.Campbell at citrix.com>wrote:

> On Tue, 2010-04-13 at 09:44 +0100, Justin Pettit wrote:
> > Apparently, the Linux GRE module is kind of buggy and supports
> > different types of tunneling in different version.  This is an OVS
> > version of GRE, which provides Ethernet-over-IP support all the way
> > back to 2.6.18 and a consistent interface.  As I'm sure you're going
> > to suggest, we should probably come up with a less generic/confusing
> > name.  :-)
> ;-) I suppose fixing the Linux GRE stack wasn't an option?

It started out of as a simple backport since older kernels don't support
Ethernet over GRE.  However, in addition to straightforward bug fixes I also
added some features that I'm quite certain will never be accepted into the
mainline kernel (primarily path MTU discovery when bridging because it makes
the bridge act a little bit like a router).  Even this turned out to not be
enough so I just finished a rewrite that integrates GRE more tightly into
OVS, as I'm sure you saw from the patch set that I just dumped on the
mailing list.

> I generally skip the stuff in datapath/linux-2.6/compat-2.6 when
> integrating into our kernel tree since none of it seemed to be necessary
> for 2.6.27 (apart from a few trivial tweaks). If this module is always
> going to be used and isn't strictly part of a compat layer for the
> in-kernel GRE stuff perhaps it would be better to pull it out of the
> compat subdirectory?

It originally was suppose to be just a backport, which is why it is
currently living in the compat directory.  The new implementation is now in
the main datapath directory.

> Unfortunately it's too late to add this module to the XenServer 5.6
> kernel but we'll need to figure out what to do here at some point.

 The GRE module that ships with the 2.6.27 kernel has no support Ethernet
over GRE (only IP).  This will completely break OVS support for GRE so we
should talk about this tomorrow.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openvswitch.org/pipermail/ovs-dev/attachments/20100413/427f2218/attachment-0003.html>

More information about the dev mailing list