On Fri, Apr 08, 2005 at 08:56:51AM +0200, Simon Derr wrote: > On Thu, 7 Apr 2005, Matt Mackall wrote: > > > On Thu, Apr 07, 2005 at 05:36:59PM +0200, Simon Derr wrote: > > > > > > > > > On Thu, 7 Apr 2005, Yura Pakhuchiy wrote: > > > > > > > On Thu, 2005-04-07 at 14:40 +0200, Patrice Martinez wrote: > > > > > When using a machine with a 2612-rc 1kernel, I encounter problems > > > > > reading /dev/random: > > > > > it simply nevers returns anything, and the process is blocked in the > > > > > read... > > > > > The easiest way to see it is to type: > > > > > od < /dev/random > > > > > > > > > > Any idea? > > > > > > > > Because, /dev/random use user input, mouse movements and other things to > > > > generate next random number. Use /dev/urandom if you want version that > > > > will never block your machine. > > > > > > > > Read "man 4 random" for details. > > > > > > > Something changed since previous versions of the kernel, I guess. > > > Running `find /usr | wc' on a ssh session generates both network and disk > > > activity, and you should not expect any other kind of input on a networked > > > server. > > > Oops, the command is actually "find /usr | xargs wc", witch causes lots of > disk activity. > > > FYI, network activity only generates entropy on a very small subset of > > NICs, and probably not the one you're using. This is good, as network > > activity is assumed passively observable/timable. > Offtopic, but why isn't the policy the same for all NICs ?
The policy is the same, it just hasn't been implemented. SA_RANDOM is scheduled for abolishment. > > > Anyway, still zero bytes coming from /dev/random, for the few minutes I > > > waited. > > > > Are you and Patrice both experiencing this on the same machine? > Both IA-64, but that's the only common point. > > > What > > was the last kernel that was known to work for you? Do you see the > > contents of /proc/sys/kernel/random/entropy_avail change over time? > > Are there any other entropy consumers on your machine? > None that I am aware of. > > I run: > # dd if=/dev/random bs=1 count=1 | od strace the dd process, please. This works fine here. > Another shell: > # lsof /dev/random > COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME > dd 1496 root 0r CHR 1,8 99952 /dev/random > > Now, find /usr | xargs wc running in background. > > About /proc/sys/kernel/random/entropy_avail: > (5 second refresh interval) That may not be sufficient resolution. The upper layers will pull from it whenever it rises above 64 and bash it back down to within 7 bits of 0. What does it do when no one is reading from it? -- Mathematics is the supreme nostalgia of our time. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
