On Sun, May 22, 2022 at 10:28:12PM +0200, d...@darkboxed.org wrote: > After looking at this more I realise now how bird is splitting multiple > ipv6 nexthops into sequences of route updates for the same prefix. > > Consequently the code doing this should also be removed. Though it seems it > works just fine either way but I get errors for the (now redundant) route > removals. > > Are we even OK with raising the kernel version required or should I try to > preserve support for the old kernel interface?
Hi The initial IPv6 multipath support required several ugly hacks in Netlink code, which i would be happy to get rid of. When Linux came with IPv6 RTA_MULTIPATH support, the initial versions were somewhat buggy, so we kept using the old API for updates (splitting multipath routes to sequences of route updates), while accepting RTA_MULTIPATH routes in scans / notifications. My notes say that minimal reliable kernel version for IPv6 RTA_MULTIPATH is 4.11. As a rule of thumb, i target compatibility for ~5 year old systems that are not EOL, for example Debian LTS. Current Debian LTS is Debian 9 (Stretch), which uses kernel 4.9, but it will be EOL in a ~month, while Debian 10 uses kernel 4.19. For kernel itself, ~5 year old LTS release would be 4.14. So i would be OK with targeting 4.14 / 4.19 as the oldest supported version and switching completely to RTA_MULTIPATH code in Netlink. -- Elen sila lumenn' omentielvo Ondrej 'Santiago' Zajicek (email: santi...@crfreenet.org) OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) "To err is human -- to blame it on a computer is even more so."
