[ovs-dev] [PATCH] INSTALL: Mention conflict with NET_IPGRE setting.

[Jesse Gross]

On Tue, Jul 1, 2014 at 5:10 PM, Ben Pfaff <blp at nicira.com> wrote:
> On Tue, Jul 01, 2014 at 05:00:45PM -0700, Jesse Gross wrote:
>> On Tue, Jul 1, 2014 at 3:49 PM, Ben Pfaff <blp at nicira.com> wrote:
>> > I found when reconfiguring my kernel that if I turned on NET_IPGRE, GRE
>> > tunnels no longer worked.  (I might not understand this issue.)
>> >
>> > Signed-off-by: Ben Pfaff <blp at nicira.com>
>> > ---
>> >  INSTALL |    5 +++--
>> >  1 file changed, 3 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/INSTALL b/INSTALL
>> > index bfd053b..8b2097f 100644
>> > --- a/INSTALL
>> > +++ b/INSTALL
>> > @@ -67,8 +67,9 @@ install the following:
>> >        obsolete and not needed.)
>> >
>> >        To use GRE tunneling on Linux 2.6.37 or newer, kernel support
>> > -      for GRE must be compiled in or available as a module
>> > -      (CONFIG_NET_IPGRE_DEMUX).
>> > +      for GRE demultiplexing (CONFIG_NET_IPGRE_DEMUX) must be compiled
>> > +      in or available as a module.  GRE tunnels over IP (NET_IPGRE)
>> > +      must not be compiled in and must not be loaded as a module.
>>
>> Hmm, I don't think that this statement is generally true (on at least
>> new kernels, OVS should be able to peacefully coexist with other
>> kernel components). What kernel version are you using?
>
> Upstream 3.2, no local changes.  I don't have any particular love for
> that version or anything, it's just the version I've been using for
> ages.  .config attached.
>
> With NET_IPGRE built in, trying to use GRE fails:
>
>      rpl_gre_cisco_register: cannot register gre_cisco protocol handler
>      openvswitch: cannot register gre protocol handler
>
> With NET_IPGRE configured as a module (and not loaded), GRE works OK.

OK, that's expected. I think that if we add "on kernels before 3.11"
to the end of your original message then it is accurate.