[privong]

> Are they independent from torvalds' kernel? I thought the kernel was patched very quickly (KPTI)?

They have to package the kernel for Ubuntu and compile it with whatever modules are standard for them. Plus perhaps applying some distro-specific patches (I don't know if Ubuntu does this), and testing.

[pas]

There's an Ubuntu Kernel Team, and they have a very handy archive:

http://kernel.ubuntu.com/~kernel-ppa/mainline/daily/2018-01-...

They have a 14MB base patch, and then a few small ones.

CHANGES mention KPTI, so it should be good to go.