On Wed, 24 Jan 2024 12:13:43 -0800 Jakub Kicinski wrote:

quoted

if that is the nftables backend, it might be also that .config is
missing CONFIG_NF_TABLES and CONFIG_NFT_COMPAT there, among other
options.  

FWIW full config:

https://netdev-2.bots.linux.dev/vmksft-net-mp/results/435321/config

CONFIG_NFT_COMPAT was indeed missing! Let's see how it fares with it enabled.

NFT_COMPAT fixed a lot! One remaining warning comes from using 
-m length. Which NFT config do we need for that one?