Right, it unifies /dev/urandom, /dev/random, and getrandom(flags=0) to all do exactly the same thing. Most modern userspaces already use getrandom(flags=0). No

Right, it unifies /dev/urandom, /dev/random, and getrandom(flags=0) to all do exactly the same thing. Most modern userspaces already use getrandom(flags=0). Nothing changes for them. They already count on the rng being seeded in one way or another. Rather, this changes /dev/urandom, which previously would give insecure randomness before being seeded. With this change, this doesn't happen any more, because it makes /dev/urandom wait until it has been seeded. In practice, the RNG get seeded by a large variety of things. As a last ditch effort, the Linus Jitter Dance will seed it. Taken together, what all the above amounts to is that the regression potential is limited to systems where: (A) /dev/urandom is still being used, rather than getrandom(flags=0), (B) the boot sequence, due to some bug, hard-depends on unseeded reads from /dev/urandom, (C) no ordinary sources of entropy, such as interrupts and input devices and disk drives, are available, (D) the CPU is so ancient as to be missing a cycle counter, defeating the last ditch Linus Jitter Dance, and (E) a new kernel will be installed on this old system. I argue that the set of machines where (A), (B), (C), (D), and (E) all hold is minuscule.