https://bugzilla.kernel.org/show_bug.cgi?id=214885 Bug ID: 214885 Summary: random.{4,7} [man-pages 5.13] do not reflect changes to /dev/random semantics since kernel 5.6 Product: Documentation Version: unspecified Hardware: All OS: Linux Status: NEW Severity: low Priority: P1 Component: man-pages Assignee: documentation_man-pages@xxxxxxxxxxxxxxxxxxxx Reporter: kerbug@xxxxxxxxxx Regression: No In kernel 5.6, the semantics of reading from /dev/random were changed significantly [1][2]. If my understanding of [1] is correct -- and perhaps it is not, I am not claiming any expertise -- /dev/random now behaves essentially like /dev/urandom, except that it blocks only in the case of insufficient initial entropy during boot, but never blocks thereafter. A few quick experiments using kernel 5.14.14 seem to confirm that understanding. This is a significant behavioral change but it does not seem to be reflected in either random.4 or random.7 from man-pages release 5.13 (as provided in Arch Linux man-pages 5.13-1). In looking thru the change history of those pages, it does not seem that there have been any updates to either since man-pages 4.10. I'd be happy to offer a patch, but the required changes are not trivial and am hestitant to contribute language on something that I don't have sufficient familiarity with. Based on my quick experiments with kernel 5.14.14, at least the following statements in random.4 seem to be entirely invalidated by the post 5.6 behavior: A read(2) from /dev/random will return at most 512 bytes (340 bytes on Linux kernels before version 2.6.12): Observed behavior with 5.14.14: It returns up to 32MB, just as /dev/urandom does. The subsection describing read_wakeup_threshold: This pseudo-file read_wakeup_threshold no longer exists in /proc/sys/kernel/random. - Glenn [1] https://github.com/torvalds/linux/commit/30c08efec8884fb106b8e57094baa51bb4c44e32 [2] https://lwn.net/Articles/808575/ -- You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.
