Hi Toke, On Thu, Jan 13, 2022 at 2:30 PM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote: > Right, but that implies we need to work on a transition mechanism. For > newly deployed systems changing the hash is obviously fine, it's the > "reboot and you have a new address" problem. > > We could introduce new values to the addr_gen_mode? I.e. values of 4 and > 5 would be equivalent to 2 and 3 (respectively), but with the new > hashing algorithm? And then document that 2 and 3 are considered > deprecated to be removed at some point in the future... Right, so this is exactly the flow of conversation I anticipated. "Let's change it!" "No, we can't." "Okay, let's add a knob." The knob I was thinking about, though, was actually a compile-time one CONFIG_NET_OBSOLETE_INSECURE_ADDRCONF_HASH, which itself is a `depends on CONFIG_OLD_N_CRUSTY` or something. This way we could gate the inclusion of sha1.c/sha1.o on that at compile time, and shave down vmlinux a bit, which would make Geert happy. Then, at some point down the road, we can talk about removing CONFIG_NET_OBSOLETE_INSECURE_ADDRCONF_HASH too. Jason
