OVS_GREP_IFELSE([$KSRC/include/net/ip.h], [IPSKB_FRAG_PMTU],
[OVS_DEFINE([HAVE_CORRECT_MRU_HANDLING])])
+ OVS_GREP_IFELSE([$KSRC/include/net/ip_tunnels.h], [__ip_tunnel_change_mtu])
OVS_GREP_IFELSE([$KSRC/include/net/inet_frag.h], [hashfn.*const],
[OVS_DEFINE([HAVE_INET_FRAGS_CONST])])
OVS_GREP_IFELSE([$KSRC/include/net/inet_frag.h], [last_in],