Hi, I maybe got confused.
First, systemd-random-seed.service will save a "seed" from /dev/urandom when shutdown, and load that "seed" to /dev/urandom when next boot up. My questions are: 1. Can we not save a seed, but load a seed that is read from ** /dev/random ** to ** /dev/urandom **? 2. Saving a seed on disk, and someone reads the content of it later, will this make the "urandom" predictable? Talking about /dev/random, it consumes an internal entropy pool, some system events(disk reading/page fault, etc) enlarges this pool, am I right? And write to /dev/random will mix the input data into the pool, but not enlarge it, right? What benefits can it get when only mix data but not enlarge the entropy pool? 3.16+ will mix data from HWRNG, does it also enlarges the entropy pool? 2015-06-15 8:40 GMT+08:00 Dax Kelson <dkel...@gurulabs.com>: > > On Jun 14, 2015 10:11 AM, "Cristian Rodríguez" > <cristian.rodrig...@opensuse.org> wrote: >> >> On Sun, Jun 14, 2015 at 1:43 PM, Greg KH <gre...@linuxfoundation.org> >> wrote: >> > On Sun, Jun 14, 2015 at 12:49:55PM -0300, Cristian Rodríguez wrote: >> >> >> Las time I checked , it required this userspace help even when the >> machine has rdrand/rdseed or when a virtual machine is fed from the >> host using the virtio-rng driver.. (may take up to 60 seconds to >> report >> random: nonblocking pool is initialized) Any other possible solution >> that I imagined involves either blocking and/or changes in the >> behaviour visible to userspace and that is probably unacceptable >> . > > I added the following text to Wikipedia's /dev/random page. > > "With Linux kernel 3.16 and newer, the kernel itself mixes data from > hardware random number generators into/dev/random on a sliding scale based > on the definable entropy estimation quality of the HWRNG. This means that no > userspace daemon, such as rngd from rng-toolsis needed to do that job. With > Linux kernel 3.17+, the VirtIO RNG was modified to have a default quality > defined above 0, and as such, is currently the only HWRNG mixed into > /dev/random by default." > > > _______________________________________________ > systemd-devel mailing list > systemd-devel@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/systemd-devel > -- Regards, - cee1 _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel