I agree about the use of UDP to be able to reuse network gear, my comment was prompted by this part of the parent's comment:
>from now on we won't have to wait for your kernel to support feature X
This is orthogonal to the issue you're discussing (for instance as a thought experiment you could design a new protocol on top of ethernet in userland using raw sockets and it won't be supported by anybody, or you could implement something on top of TCP in the kernel and it'll work everywhere).
I just wanted to point out that outdated kernels aren't a fatality, it's a consequence of bad industry practices (in particular, although not uniquely, by Microsoft with its Windows OS). On Linux everything is updated together and the kernel is mostly just another package, so it's a non-issue. It's also means that applications don't have to package a custom updater (and all related infrastructure) by themselves.
Supporting a new protocol on top of IP using raw sockets can be supported by endpoints that are running your software. Except, of course, if you go through NAT or any of these "middleware boxes" that litter the Internet.
> On Linux everything is updated together and the kernel is mostly just another package, so it's a non-issue
Except say on my linux (ubuntu), yes the kernel is patched, but the version doesn't increase very often at all sadly. Yes I decide to run the mainline kernels since I'm on a laptop and I find that beneficial, but it's not the default of most linux installations I believe.
>from now on we won't have to wait for your kernel to support feature X
This is orthogonal to the issue you're discussing (for instance as a thought experiment you could design a new protocol on top of ethernet in userland using raw sockets and it won't be supported by anybody, or you could implement something on top of TCP in the kernel and it'll work everywhere).
I just wanted to point out that outdated kernels aren't a fatality, it's a consequence of bad industry practices (in particular, although not uniquely, by Microsoft with its Windows OS). On Linux everything is updated together and the kernel is mostly just another package, so it's a non-issue. It's also means that applications don't have to package a custom updater (and all related infrastructure) by themselves.