Problem scenario
You want to install uffd on Linux.
Solution
uffd refers to "userfaultfd" that is often available on Linux.
Type "man userfaultfd" to see if it is available.
userfaultfd is a system call (as can be discovered by running "man syscalls" and searching for "userfaultfd").
To read about support for userfaultfd, see https://github.com/rr-debugger/rr/issues/2852.
If you have a modern Linux system without userfaultfd, please let us know (and run "cat /etc/*-release" and provide the results of this command in your response). We would be curious to find out what distribution does not have it.