linux-kernel - Entropy Pool Contents

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Date:	Thu, 23 Nov 2006 00:54:03 +0100
From:	Gunter Ohrner <G.Ohrner@...t.rwth-aachen.de>
To:	linux-kernel@...r.kernel.org
Subject:  Entropy Pool Contents

Hi!

(PEBKAC warning. I'm probably doing something dump. I just don't know
what...)

I seem to have an entropy pool on a headless machine which is not nearly
empty (a common problem in this case, I know), but completely empty and
stuck in this state...

Hornburg:~# cat /proc/sys/kernel/random/entropy_avail
0
Hornburg:~# fuser /dev/urandom
Hornburg:~# lsof | grep random
Hornburg:~# cat /proc/sys/kernel/random/entropy_avail
0
Hornburg:~# dd if=/dev/hdf of=/dev/urandom bs=512 count=1
1+0 records in
1+0 records out
512 bytes transferred in 0.016268 seconds (31473 bytes/sec)
Hornburg:~# dd if=/dev/hdf of=/dev/random bs=512 count=1
1+0 records in
1+0 records out
512 bytes transferred in 0.031943 seconds (16029 bytes/sec)
Hornburg:~# cat /proc/sys/kernel/random/entropy_avail
0
Hornburg:~# fuser /dev/urandom
Hornburg:~# fuser /dev/random
Hornburg:~# lsof | grep random
Hornburg:~# cat /proc/sys/kernel/random/poolsize
4096
Hornburg:~#

Also causing disk activities doesn't help at all. (Two disks on a Promise
PDC20268 controller.)

The system runs a rather ancient Debian Sarge 2.4 kernel:
Linux Hornburg 2.4.27-3-386 #1 Thu Sep 14 08:44:58 UTC 2006 i486 GNU/Linux

However as the machine itself is also ancient, the 2.4 seems like a good
match. And also 2.4 ought to have a refilling entropy pool, doesn't it?

Maybe someone can shed some light on what's happening here...

Greetings,

  Gunter

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