On Wed, Oct 01, 2003 at 04:35:23PM +0300, Oded Arbel wrote: > On Wednesday 01 October 2003 15:54, Muli Ben-Yehuda wrote: > > On Wed, Oct 01, 2003 at 03:31:44PM +0300, Oded Arbel wrote: > > > I'm having a problem with a server, where apparently I don't have any > > > entropy left in /dev/random : > > > # sysctl -A | grep random > > > kernel.random.entropy_avail = 0 > > > Why not use /dev/urandom? that one never blocks. > > 1. its lower quality
I don't know what's your application, but I really doubt it matters. > 2. Its not my software, and I don't feel like messing around with the source > code right now. I'll do that if I'll have no choice, but seeing as /dev/ > random is important to have, I though I'd try to deal with the source of the > problem first. Unix 101: use a symlink. Even better, recreate /dev/random with /dev/urandom's minor number for this application. > > It's possile, yes. Looking at the code (2.4.23-pre5, but I doubt there > > were major changes in this area in the vanilla kernels), > > I'm not using vanilla - I prefer buttermilk myself, but I have grsecurity > patches. AFAIK, grsecurity shouldn't turn off any entropy generation - it > relies on good quality entropy pool to add more randomacity to stuff the > kernel does. Have you verified that it's not doing anything fishy? > > the relevant > > function is add_blkdev_randomness, which works at the block layer, not > > the file system layer, so it doesn't have much to do with > > reiserfs. > > Then, could you please offer a hypothesis as to why my dev/random is > empty ? Something exhausted it, or its not getting filled enough. You can trace calls to it to rule out or confirm #1, or you can find out what exactly replenishes it with your current kernel, and then cause it to be replenished. Sorry I can't be more specific. > > Quoting from drivers/char/random.c for ways for you to > > generate entropy: > > As I understand these need to be implemented in the kernel, at the device > level. is it possible that some are "turned off" or something ? Unlikely in the vanilla kernel, don't know about your kernel. -- Muli Ben-Yehuda http://www.mulix.org
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