OVS_GREP_IFELSE([$KSRC26/include/net/checksum.h], [csum_unfold])
OVS_GREP_IFELSE([$KSRC26/include/net/netlink.h], [NLA_NUL_STRING])
OVS_GREP_IFELSE([$KSRC26/include/net/checksum.h], [csum_unfold])
OVS_GREP_IFELSE([$KSRC26/include/net/netlink.h], [NLA_NUL_STRING])